Worst Vocalist - Charlie Dominici (Dream Thater's first singer...)
Sean Killian (formerly of Vio-Lence...)
Worst Bassist - kinda hard to say, there are so many crap bassists that only play root notes... well shit, not EVERYONE can be like Steve Harris and Steve DiGorgio
Worst Drummer - There is a black metal band from L.A. named Intralus who's drummer is absolutley horrible.. when he does a fill, he does it so sloppy he comes in on the offbeat and instead of bass-snare during the hyperblast it becomes snare-bass... and by the time the song is done the tempo has gone up by 231%.
Worst Guitarist - Steve Dougherty, hand down. This guy used to be in a British copy of Van Halen... after listening to this dude bend out of tune and exhaust all possible configurations of the pentatonic scale, Kirk Hammet isn't so bad to listen to...