Goku barely dodging Vegeta's blast is very similar to 18 barely dodging Trunks' blast. The way the saw the blast, their reactions when dodging and their following commentaries on their speed and power are very much similar. So I tend to compare both instances moreso due to their similarities:
Goku dodged Raditz's attack in a more urgent, visceral way, while screaming. Seems like he'd be in the end of his life receiving that head on. Raditz also stated he'd make his attacks better as time went by. He likely made it slower so they could have an easier time dodging it.
And Trunks underestimated 18 to a degree. He said they wouldn't kill her since she's 18. When she dodged, they were clearly a little frustrated and Goten suggests going a notch up, meaning that blast probably wouldn't kill 18, since even while underestimating her somewhat, likely based on the level she used to battle them, Trunks still said she wouldn't be dead. So an 18 that used her full abilities while dodging and kinda surpassed Trunks' estimations as he expected it to hit, would likely not have suffered heavy damages with that blast. She would likely be damaged, but I'm okay with that blast being slightly above her, as Vegeta's 18k blast gave Goku even more problems under a very similar scenario, dodging scene and similar compliments laid out by Goku after that. I didn't say that merely dodging it would necessarily imply the blast was only slightly above. It depends on the way the scene was built, the characters reactions to the blast, and it also goes back to Raditz saying he'd be increasing his attacks slowly and likely not wanting to kill them right away.
That is irrelevant to the point. If the argument is that the blast from the Super Saiyan kids could not be significantly beyond Android 18 because she managed to dodge it, then the point still stands that Goku evading Raditz' blast is a counterexample to the claim because even you agree that the blast would have decimated Goku. I honestly don't care for the numerical gap all that much. A 450 vs. 460 isn't representative of a critical wound which would have happened if the blast had connected with Android 18. You claim that you go based on reactions and Android 18 shitting bricks would imply a significant gap.
Regardless, we have examples in the forms of
Vegeta vs. Monster Zarbon and
Trunks vs. Cold & Frieza in which the weaker fighters were capable of escaping their blasts. The latter scene doesn't even need to frame the scene in any way to make it obvious that Trunks' blast would have significantly damaged Cold and Frieza, if not, killed them. Furthermore,
Vegeta evaded a point-blank blow from Recoome which would have critically wounded him had it connected.
When we look at it Goten's and Trunks' conversation, it's evident that Trunks misjudged Android 18.
Chapter: 453 (DBZ 259), P8.4, P9.1-7
Context: as Trunks and Goten fight No.18 in their Mighty Mask costume
Trunks: “Da-dammit! We can’t win like this!”
Goten: “Let’s turn into Super Saiyans, Trunks!”
Trunks: “That's it! We’ve got this thing on, so she won’t be able to tell who we are…Alright! Shall we turn into [Super Saiyans]?”
Goten: “Yeah!”
No.18: “…He really is a weird bastard…His arms and legs are extremely small for his body…And he’s so unusually strong…”
*they become Super Saiyans*
No.18: “!!”
Trunks: “Either way, we’re at a disadvantage in this getup, so we’ve got no choice but to settle this with a kiai cannon!”
Goten: “Eh! But will she be alright?...”
Trunks: “
Don’t worry, she won’t die if we do it appropriately.
She’s No.18…”
Goten is the one warning Trunks not to use a ki blast. Trunks responds by claiming that she is powerful enough to handle it because she is Android 18 who used to be stronger than the strongest people they know. Right before launching the blast, Goten warns Trunks again.
Chapter: 453 (DBZ 259), P10.1-2
Context: as Trunks prepares to fire a ki blast at No.18
No.18: “…I see…Super Saiyan, huh?...I finally know your identity, boys…”
Goten: “
Don’t do it at full force!”
Trunks: “I know, I know!
Trunks' response was one you would expect from a child who is constantly being reminded by a parent as to what not to do. Trunks overestimated Android 18 and her. In any case, Android 18 was petrified and had no idea whether the kids actually held back on the blast. It should be obvious based on her immediate response that the blast was easily above her. It wouldn't be an outrageous blast if it were within her capabilities and honestly, I don't really have any idea why the framing of the scene even matters here. Adjust Goku's angle against Raditz and you would literally have the same scene.
