Well, they weren't at the Prince last December when I was there. It was the old usualy assortment--a few ladyboys, lots of older men, and some younger guys here and there--but the same ones as I'd seen on previous visits (!). In fact, one who has a great body I think used to work as a go-go, but now is relegated to the Prince.
I much prefer the (still-open, I think) cinema near Saphan Kwai, on the left and in one block (on the left side as you take the BTS from Siam Square). There was a post about this in December and January, I remember adding to it.