Met 100's of very very nice celebs and those who are quite well know too. Easier if i just list the ones who I thought were miserable jerks or who weren't that nice.
Edward Furlong (Young John Connor from Terminator movies) Loathsome and disinterested. Right up himself.
William Shatner, Beyond cretinous and spoilt. So far up himself he can tickle his own tonsils. Seems to be getting worse as he gets older.
Herb Jefferson jr Use to play Boomer on the original Battlestar Galactica series. I met him about 4 times now and he is always the same. Will ignore people when they speak to him and generally looks like he might self combust with anger. Weird , not nice guy.
Forget his name but this next one did the male HOLLY on Red dwarf. Miserable disinterested git.