There are some nu-uh parts but for majority of it, i dont see anything typically "incorrect" guide books can most definitely be used as back up/ evidence. Dont know if people would just accept it though.
It can only be treated as canon in a case by case scenario. For instance, we can take uncontradicted things such as Kuririn being the strongest human as fact from it, yet can't possibly take some battle power readings such as Piccolo Daimao > BoZ Tenshinhan > Kami as reliable.
That is something I haven't considered before. After all, the power chains in the Guidebook are very flawed.
Even with all our battle power knowledge, I would still much rather have explanations of character details in the Guide rather than just Battle Powers.
If you want, me personally. My interpretation is just as good as their's. At the end of the day, the thing people come to and see first is not the guidebook. The guidebook doesn't speak for the show, the show speaks for the show. The guidebook is simply another person's interpretation of it.