I will only make one comment here as Rudy has already layed it out for us gentlemen & the only reason for this comment is that I personally believe it is on topic here.
THC has many affects on the body & mind, but lets focus just on the body for now as mental effects are a moot point when referencing bodybuilding.
THC is known to change the way an individual "experiences" pain. In other words the chemical nerve signals being carried from the pain source to your brain get interpreted differently IN the brain. After leg day or deadlifts where you have a hard time dragging yourself from the gym to the car, have a smoke then and you will see exactly what I mean.
Also (and this is contreversial) I have found personaly that I obtain a much better nights sleep after a smoke before bed. I don't move at all, wake up in the exact same position I fell asleep in and based on what I know about healing and growth, this is a good thing!
Again I just wanted to attempt to tie the relevance of this "recreational drug" to bodybuilding. I mean you no dis-respect Rudy and I suspect you will close this thread soon anyway.