Goku was really using an invisible Kaioken x10 vs true form Freeza

[freezamite]

Piccolo's sentence isn't ambiguous whatsoever.

Nobody said it's ambiguous. It's apparent that Goku got more serious when Freezer fought at 50% of his strength. I'm just saying that this wasn't ambiguous either:
http://mangalife.org/read-online/Dragon-Ball-chapter-35-index-2-page-11.html
Or this:
http://mangalife.org/read-online/Dragon-Ball-chapter-140-index-2-page-7.html

For a scoutter, it doesn't matter if you're fighting or standing still, or if you're aggressive or pacific (except when those emotions disturb your ki and as a consequence your battle power diminishes, but that only happens to the SSJ and Nappa in the whole series), your battle power is your battle power.
For someone sensing Kis, on the other hand, those are things that influence one's perception. Of course, unlike the scoutters sensing Kis also allow to guess if someone has goodwill or if he is evil or if someone is aggressive or not (so it has its own uses that a scoutter wouldn't be able to replicate), but when it comes to measuring power, it's just not comparable.
Was Goku crazy because he only realised Vegeta's true potential after he got more violent? Why is Yamcha commenting on the fact that Goku wasn't even fighting if that supposedly doesn't influence one's perception?

And if you prefer to think that Goku's battle power changed, there's also this that shows that you don't need to be at your maximum power to use the KK:
http://mangalife.org/read-online/Dragon-Ball-chapter-91-index-2-page-1.html
See? With the same level of KK, Goku slowly increases his strength to fake a normal power up and trick captain Ginyu (or he slowly increased his KK level from 1.X to 2, it doesn't matter) into believing he is much stronger.

Both of those aspects could explain Piccolo's comment without breaking any internal rule of the manga. And we have good examples of Goku doing this before, unlike him surviving a punch that could defeat him while using the KKx10... without using the KKx10.
You can choose, or Goku's change of attitude was perceived by Piccolo (in fact, that's what we normal human beings do when going from simply sparring to fighting seriously, so I don't think why it would be that strange for Goku to do the same) or he did the same he did against the Ginyu force and had a bit of Ki on reserve while still using the KK.

You're just making the scene more difficult than it needs to be. The Manga is very clear on what Goku's reserve power is. What you seem to do is add so many unnecessary portions to a rather simple story. Dragon Ball isn't complex.

Well, I won't argue if it was complex or not. What I'll say is that it not always was as simple as some of you think (otherwise Nappa would be 4000 like the Daizenshuu states because he clearly lost to Goku, but he was stronger than Goku instead. And there are dozens of examples like that).
For some of you it's as if the manga was written by a 4 year old kid, with no internal rules nor any logic besides "what's happening is cool". And that may be true for the anime, and I can even understand that if someone learned about the series through the anime this could influence him, but the DB manga per se was pretty good when it came to power scaling, it played with a lot of factors when defining someone's performance in battle, and it often played with those factors to give what in other mangas would be pretty simple scenes a bit of depth.

Freeza knew Goku was hiding power and called Goku out on it. Why would he continue using Kaio-Ken x10 if that wasn't the power he was clearly hiding? Your explanation doesn't make a lot of sense and creates more confusion. Kaio clearly said Goku was using the Kaio-Ken x10 well after these statements are made, so the reader knows what power he was using.

We saw Goku using the KKx20 with less damage to his body than the KKx3, so it's obvious that what Goku was hiding could also be KKx11 to KKx19 (although KKx11 to KKx15 at short bursts would be more realistic in a normal battle environment).

And even if Freezer could anticipate Goku was hiding some power:
1. Vegeta also knew Goku could use the KK in the earth, and he was still surprised when Goku suddenly activated the KKx2.
2. SSJ Goku also knew Freezer was only using half his strength, and even then he was surprised when Freezer suddenly attacked with 70% of his Ki.
3. Freezer knew Goku was hiding power, but he was still caught off guard when Goku activated the KKx20.

So him suddenly anticipating a KKx10 activation without even looking is not a realistic explanation. Even less that supposed KKx10 activation is limited to those two pages and we have to assume that:
A. Another rule is broken when suddenly non-KKx10 Goku is able to survive against hits that would defeat KKx10 Goku.
Or
B. Freezer anticipating when Goku activates or deactivates the KK to modulate his strength to not kill him.

Both of those options are impossible if we believe what we're told about those characters.

As for this: "What is clearly specified in the manga, and we have dozens of examples of it, is that no one can survive a hit strong enough to beat someone with 10 times as much power as one is currently using"

Goku's power was going down and he was still taking attacks from 50% Freeza. He's easily 10x weaker or more.

You act as if Freezer wasn't clearly torturing Goku without the intention of killing him here. And here Goku is visibly tired, Freezer (like any other character) can clearly see that Goku isn't at his 100% (and obviously, Goku was still going with the KKx10 in those pages, he had to do so at least until he launched the Genkidama) and that is to what Freezer adapted (everyone could adapt to something like that).

And that little sentence about "admitting defeat" very easily can apply to you, since you seem to believe your assessment of the story is better than everyone else's. Try to be a little more reasonable instead of hand-waving everything others say.

The difference is that unlike some of you, I don't have any problem at admitting that some other interpretation of a fact may be better when I'm given good enough reasons to do so.
For example, I did it in the thread about Nappa's strength when we were discussing if Vegeta's comment on Gohan's BP was about Gohan or about his Masenko. I said it was about his power, I was given good reasons that were enough to convince me it was about his masenko, and I admitted that as soon as those reasons were given to me.

But you're not giving any good arguments here, you're just grabbing Piccolo's sentence and interpreting it in a way that clearly breaks the manga's internal rules only because if done like that it seems to support your cause. But I've already given much better explanations to that sentence, explanations that besides being as good as yours when isolating Piccolo's sentence from the rest of the manga, but that unlike the one you give they don't break any internal rule of Toriyama's work.

And of course, trying to argue that "Dragon Ball wasn't complex so there were no internal rules" isn't a valid argument either, because there clearly were internal rules and the author respected them for the most part of his work.

Not to mention Gohan, with a power level of 1, surviving Raditz's attack, whom although weakened, was easily many fold above Gohan, or freaking Vegeta base surviving hits from Kid Boo (whose powers was 400x+ Vegeta's) without getting unconscious. One-shot gaps aren't linear.

One-shot gaps aren't linear because the strength those hits are given has to be taken into account as well.
Gohan surviving Raditz's attack can be explained because Raditz read Gohan's 1 battle power, but he clearly miscalculated to which extent he was injured (he had the same strength than a very badly injured Goku that had multiple bones broken) and when he hit Gohan he was still in huge pains from Gohan's attack (which further diminished his available strength at that moment). With all of that on mind it can be explained that his hit didn't kill Gohan, he didn't realise how weakened he was and with the dozens of units he had left even without taking into account the pain he was feeling the strength of his hit was even weaker than it should have.
I'm not going to deny that it was forced (as forced as the saiyans Zenkays in the Namek saga, that went from small to huge multipliers depending on the needs of the plot) but there still were a lot of factors that could be used to explain that (it's not like Raditz was at 100% of his strength and hitting with all he got, which is the requisite for a 20-30% difference to one hit kill someone).

Regarding base Vegeta surviving Kid Bu's hits... was Kid Bu fighting with all his strength there? No, he wasn't. And Kid Bu cold feel Kis and adapt to them. Heck, even Satan survived a punch from Kid Boo, which proves that Kid Boo simply enjoyed torturing his victims instead of brutally killing them with all his strength like Vegeta did to Kiwi, Zarbon or Dodoria.

 

[Pyro]

The colored manga doesn't give Freeza a Kaio-ken aura. He's simply at an angle behind Goku as he's kicking him. Eh?

 

[freezamite]

The colored manga doesn't give Freeza a Kaio-ken aura. He's simply at an angle behind Goku as he's kicking him. Eh?

You sure? Look at the image, and you'll see how both Freezer and Goku had an aura there (it's made pretty clear by the bit of the aura that goes from Freezer position to his silhouette as he jumps from the ground) and that was also coloured in red.
The coloured edition of the DB manga is really good, but it's not perfect as this scene demonstrates.

 

[SuperDragoon]

I screw up by the painter doesn't disregard that Goku is only colored Kaioken half way through the battle consistently. Toriyama actually did have at least some imput and likely has a set idea on what colors things were considered he occasionally colored. No official material states that Goku had an invisible kaioken. No guidebook. No author statement. Nada. Unless Toriyama comes out and says so, it doesn't exist.

 

[Jerk Store]

Lol......... Those two deserve each other.