Catman, Colesdad, Gentlemen, than you both.
Yes, Catman, they have a better explanation there in Colesdad link than I can put together right now as far as how to do it and why.
I will report on my own experience with the wash here. And yes, it is my first time washing and holy crap! I can see the brown water left behind upon rinse and I think to myself "I used to smoke all of that".
While I too cringed at the idea of bud washing when I first heard of it (read of it) I have warmed up to it nicely. It makes sense that removing dirt and other junk that gets in there during the grow (and leaving the plant and trichomes behind intact) is a good idea and when compared to food, I was sold. I will let you all know how it goes but I don't expect any surprises there.
A careful check of the buds right after washing and hanging reveals all trichomes are intact on the buds. I am not missing heads or anything from what I can tell. Of course I will be checking and re-checking through the day to confirm but thus far it seems clear that the trichome heads are not affected by the wash.
Buds are very buoyant! They want to float. I had to push them in there and shake then. It seems they are impermeable as well as the buds seem to come out fairly dry after the first complete dunk. And think about it. In nature, it rains! Right on the bud. Multiple times in the life of a tropical sativa in its natural habitat. So nature does wash them buds as well to some degree.