So what, even if it spits out new trichomes, they would be clear and non-psychoactive. I think that the people that put them in the dark do it to ripen those that are already there.
I think it's just a whole bunch of voodoo - if you put a plant in the dark for 3 -5 days the trichomes will continue to oxidize to translucent or amber - even the stalks of the trichomes will turn from clear to white in those last few days.
So the result is that when they finally see the plant after a few days, the heads have done their last bit of maturing, and the stalks have turned translucent, making the plant look more white/frosty than it did 5 days ago. Now imagine what that plant would done those 5 days if its trichomes continued to oxidize BUT it had light and therefore could photosynthesize to swell its calyxes a little bit more, and suck the last bit of nitrogen out of the fan leaves.
My personal method is to give a good flush 10 days to 2 weeks out, then they get nothing but water. I let them get light all the way up until I snip them. I also like to cut during day period because, in my experience, the fan leaf stems are stiffer and easier to snip at the base of the stem.
I have also heard of guys going in after 5 days to find their nugs coned over with spider mite webbing.