Worst case I ever saw in an actual work environment was a function called:
AsicMonsterOverrideBurstSizeAndInterval(int, int);
The worst I have seen so far was >200 characters (216 if I remember it right). The median of the lengths over the whole repository was (if I remember it right) ~60 characters. Yes, I complained about this but some things are to messed up to be fixed.
I'm of the opposite opinion in that I find the underscore between words harder to read and adds "useless" horizontal space.
IDon'tBuyThis.WhyIsStandardTextThenClutteredWithUselessSpaces?AreAllTheBookAuthorsWrong?OrDoesCodeHaveSomeMagicComponentThatMakesItEasierToReadIfSpacesAreOmmited?WhyDoesYourForumPostContainSpaces?IDoUnderstandThatCamelCaseIsMuchEasierToType.AndOfCourseShortIdentifiersAreAlwaysEasyToRead.ButForLongerIdentifiersIDoNotBelieveThisTheory.
I confess sometimes I use CamelCase as well. Especially if I code in contexts where all others do it that way. But as I said I do not buy it. In general I try to avoid it.