I've stopped going in the MP3 clinic for the time being, because I only seem to be interested in doing recreations of my favourite songs at the moment, and there's only so far you can go down that road before disappearing up your own arse.
That said, I always regret posting stuff in there once I've done it, because 99% of people don't understand the genre, the history of it and the stylistic cues and/or mix values. It's a completely wasted exercise. I know myself that my stuff sounds right, I have good enough artistic judgement to hear that for myself. I suppose that the only reason I post stuff in there is because there are ears - any ears - who will give it a listen. Like Greg, I realise that there is barely 1% of people in there that will give a worthwhile or apposite comment. The rest just infuriate me, because their stuff sounds like shit.