Puzzling question. It can only be a fetish in the AIDS-context. As long as AIDS wasn't around, nobody was speaking about BB or even about anal. Anal seemed farther away from gay men than anything you could imagine. Since AIDS the only focus is unfortunately on anal at the cost of all other fetishes.
I suspect that this post is an April Fool's joke, but in case it's not: wrong.
Everyone had anal sex ALL the time before AIDS. No one wore condoms. It wasn't a FETISH, but everyone was either an anal top or an anal bottom, and people who didn't do anal at all were shunned.
Right after the news of AIDS came out, lots of people stopped ever doing anal (personal ads that said "health conscious" were from people who wanted to let you know they didn't). They went back after the news came out that condoms stopped the virus.
Pre-AIDS, anal was the ONLY thing that counted as having sex at all.
As it can only be a fetish in the AIDS-context and gets all attention away from other fetishes, it is not a valid fetish anyway.
The logic of this eludes me. Fetishes are always in a cultural context. There were no cigar fetishes in 1245 Germany. Bareback is cum-fetish porn; yes, the fact that it's dangerous is what makes it exciting, not unlike an extreme sport. People have always had various kinds of danger fetishes, mostly around the risk of getting caught having sex in public, and unfortunately disease fetishes are nothing new either.
Come to think of it, I don't even know what you mean by "a valid fetish." What is validity with respect to fetishes? Who decides? Where did you get this strange notion?


































