Why on earth would a UFC fighter not do juice; why on earth would anyone think they shouldn't. They juice pitbulls and chickens for the same shit and it's considered awesome because it makes for some crazier shit in there. I used to have a guy I knew bring in the gaffs they attached to the chicken feet explaining to me that with these, when the action really gets good, you get bodyparts flying off and shit...legs, wings, heads. Just like throwing them into a blender.
since squadfatter would rather insult you than answer your question, i will.
the UFC, in an attempt to gain some kind of legitimacy as a true contact sport and make it household instead of the bloodbath it used to be back in the days of UFC 1 etc. it has of late been testing and suspending for testosterone metabolites.
sean sherk for example was suspended and had to give up his belt. this is pretty strict and a no fucking around approach to cleaning up the sport.
basically, they are trying to make it mainstream, and as acceptable to the public eye as boxing, without the corruption. a legitimate sport, not a massacre for blood thirsty fans.
i dunno if this will work, but the sport itself is making leaps and bounds and i hope to see it continue as such.