Neither - there's a time and place for everything.
not good its very bad in my point of thoughts
well it's not quite nudity but it is very close it's called DearS
That solely depends on the occasion. Usually public places aren't a great idea. But in the privacy of your own home, go nuts.
there is Bokutsatsu tenshi dokuro, high school of the dead, Green Green, Elfen Lied (u gotta watch that one, it is totally nudity.) that's it i know so far. dragonball is another good one