to each his own
The short version of my take on this question is that I feel as though work and play should be kept relatively separate at least as far as production and inspiration goes.
You could say that I don’t want to potentially have to rely on anything besides *me* to make music or be inspired - whatever. Now I don’t think there is anything wrong with turning to outside influences for a different perspective on things, but I am too weary of the potential for that to turn into a situation where I am inhibited and unable to perform without “help”.
(I guess I’m tweaky this way. I try not to drink when I get stressed, I try not to take sleeping pills when I can’t sleep, minimize pain killers when I have headaches… If I am stressed, suffering from insomnia, or have a headache, it is likely that I should figure out why this is happening and fix the problem instead of ignoring it).
I know enough musicians, many of whom I have worked with or recorded, that incorporate getting stoned into their regualr routine. Perhaps it gives them added inspiration or removes a few barriers of consciousness, thus allowing a more direct flow of thoughts - letting you compose or play more naturally. I can attest to this, seeing as how the maelstrom of thoughts and emotion constantly circling through my mind *really* gets in the way when I sit down to work on music in front of a computer. I mean… sometimes it seems as though if I lean back and close my eyes my brain takes off and the song writes its self in a few minutes.
However when I sit down in front of a computer I get a window of approximately 20 seconds until my brain is in a totally different place. After a minute I zone out and start punching out acid riffs, creating new patches and playing with filters.
Although the side effect of that unwelcome distraction is that I sure do have a large patch library, and I can probably crank out a wicked improv live set, my tracks never really got anywhere because after a certain point they seemed to hit a wall. :?
But… a simple solution for this is to pre-arrange the songs with a pen and paper
I find that this method is the best way for me to get my thoughts out in a coherent fashion. ie. “This is what is in my head - this is what I want the song to be” - and actually writing it out with my hands was the only way to make it happen. Then I can sit in front of the computer, design sounds a tweak stuff to my hearts content. When it comes to programming all I have to do is copy the paper to the sequencer and make some adjustments or additions 
So that’s my way. Please note that I am not passing any sort of judgement on anyone else… I don’t have a problem with other people getting stoned / getting drunk (I’m known to sit with a bottle on occasion) and producing, playing or engineering. Hell when I do live sound engineering I drink Guiness like its chocolate milk (partly because it’s free…
) - but that’s live sound, not music production. If you’re ever done live sound I’m sure you can understand.
Anyway, yep… to each his own, right?