Drugs don't do shite, look at Led Zeppelin, they all got into heroin (Just before 1980) and their music went down the shiteter! But their older stuff was awesome.
This is what I think.
I really don't like Satriani.
(EXPLANATION: if you want to play fast all the time, with no feeling at all, you need really good technique to redeem yourself. His left hand's fine, but there's no picking, and a lot of it's all horrible tremolo tapping. Petrucci, Morse and Buckethead are my favourite - not just because they are inhuman shred machines, but they are creative, they have superb right hand technique, they can play with real feeling, and they don't try and make their solos sound fast through a jumble of legato passages, they think about what sounds cool and they play it. Rusty Cooley and MAB are just tossers.)
John Frusciante clearly doesn't try to make his solos a stream of fast, showy, brainless shred, but he does what he does amazingly, and he is an integral part of the sound of one of the most popular bands today, so he must be doing something right.
But feel free to disagree. I just really don't like Satch :(