When did asslicking/rimming become a staple in lesbian porn?
 

I notice that almost every new lesbian clip/ photo shoot out there features ass licking. This seems to be a new trend?
In the 90es girls were even weary of licking pussy, let alone ass. Nowadays, they more and more go for the ass, to the point of sticking the tongue inside the ass hole. Even the new issue of Penthouse features ass licking.

When did rimming become "mainstream" so to speak? I mean, it's a kind of a kinky fetish isn't it?
And what about the health issues? Does the fact that there's a lot of bacteria in the anus get ignored?

I noticed that too. Women tend to have higher standards for hygiene than men, so perhaps they're more comfortable doing it with another woman. The fact that it's 1) very pleasurable, and 2) somewhat risque, only makes more people want to do it and have it done to them.

Give and let give, so to speak. As for fecal matter, it's not much of an issue unless the recipient is filthy (a bad smell is a dead giveaway) and you intend to stick your tongue into the rectum, which is somewhat difficult. Essentially, the honor system is in play.

first i can recall offhand was seeing Janey Robbins and Erica Boyer in Loose Ends - which was i think early 80's LA porn - all dreadfull boob jobs, harsh light, poor video, and dreadful soundtrack....
it's making me hard just thinking about it :-)

Isn't the anus "cleaner" than the mouth? Or is that folklore?

I don't know where or how the trend started, but I appreciate it very much.

Never had the urge to lick someones poop hole. http://en.wikipedia.org/wiki/Anilingus

I guess an extensive volunteer research programme is in order.

It's one of those taboos, I think. I happen to think the spectacle is very watchable.

I haven't seen much 70's lesbian porn, but the girl-girl scene in Caligula features a few seconds of Anneka Di Lorenzo rimming Lori Wagner (of which we see more in the still photos in Penthouse). That was somewhere around 1977 or so. It was fairly common in Vivid videos in the 80s, because Ginger Lynn did everything, and Bruce Seven was an excellent director of lesbian porn.