For the last 20 years or so, gay men have ben bombarded with the "always use a condom!" message. The idea of taking a load of cum up our ass has been branded a "very bad thing". I think this, in turn, has caused a small amount of the gay population to fetishize cum, in way that it never was before.
It's one of those things where you always fantasize about what you can't have (bareback sex). But then if someone with all these fantasies finds themselves HIV+, then they not only feel it's ok to indulge in these fantasies, but push them to the limit.
SO you end up with a cutie like Dawson taking 50 loads over the course of a weekend. I've seen both parts of Dawson's 50 Load Weekend, and it's pretty good. It does certainly focus on anal sex, though there is a scene where Dawson sucks off 6 or so guys (and then saves their loads into a cup, so they can be inserted into his ass with a turkey baster later).
I'm assuming you've checked out the treasure island website? They have a lot of pics and very explicit descriptions of all the movies.

