I don't think it's cliched at all. Like you said, it happens all the time and with the nature of gay sex, there is a hightened chance of contracting AIDS. Most off my gay male friends get tested every six months because they're aware that they're in a high risk group. So not a cliche, just reality.
You have to be pretty screwed up, way past how I would perceive Bden's dabbling, to shoot up; serious drug taking. Besides, unless it was a one-off drug experimentation thing, the others would notice his mood swings and probably be on his case. That wouldn't fit in with the HIV going undetected.
*back to my usual rambling. lol