I love Hefeweizen and Belgian Whites...
I dislike anything overly watery, which is most American macrobrews, and I'll even specify Coors in that. Also, Budweiser does something strange to their light that I think tastes of rust and failure.
Any brewery that thinks calling it a lager or a pilsner is an excuse for serving yellow soda water is the worst.
ETA: I have limited experience with the style, but I've had several trappist ales that I thought were a bit... funky (limburger cheese on the nose), and although I actually thought it was a decent brew, they made me sick to my stomach afterwards in a way that no other beer (or liquor) has- despite imbibing far more of it!