If people deliberately try to have multies that behave differently from each other, well, good luck to them - I couldn't be bothered with the effort.
If people want a new start in a new place, well, fair enough, I no problem with that, and can respect that desire. Who does it hurt? If they are 'evil', their true colours will show up eventually.
All I really care about is whether a post is interesting or constructive or informative or funny or a combination of those things or not. Sometimes, patterns emerge and I can make predictions about how interesting/constructive/informative/funny a post might be given the username, but even then, people can make posts outside of that general pattern.
Sometimes I almost feel like writing someone off because their posts are particularly dumb, and then in another topic, they shine!
c'est la vie