Anything wheat!! Sweetwater brewing out of ATL has some really good stuff. I have just recently started brewing my own and have a mexican style brew in the kegerator right now with a wheat style in the fermentor!
Well I used some purple power @ 1:1 with a nail brush and it made a noticable difference but I still have some spots. If I can ever get it clean is there a way to prevent this short of putting a seat cover on?