Gotta say, the fact that you even talk about 'programming' on a matter regarding people's orientation and their physical and emotional needs kind of says a lot about how deeply you understand the human condition.
Having said that, it seemed to me that the most noticeable characteristic of Joe's partners was that they were deadbeats attracted by an easy ride.
Perhaps this was less noticeable to you because this is closer to your world and your idea of 'everyday', too.
The truth is that for some people a secure future that they don't have to work for is very attractive. If there are enough drugs on hand (another major factor in these guy's lifestyles) then I guess such people can be pretty flexible about matters of 'orientation'.
In a similar way, I'm told that there is no small number of ladyboys in Thailand who are not even sexually attracted to men.
They get to see it as not a big deal, and if that's how they see it then, of course...it isn't.