Its got nothing to do with being gay.....
Its all about two people who usually have very good jobs who can work full time because they have no kids. And because they have no kids they save a ton of money right there.
My parents always had rental property when I was growing up and it got so tough to find "good" tenants that all they would rent to were gay men. The best renters there ever where. They would move in and ask my Mother "Concetta, do you mind if we paint this place and put all new window treatments, will pay for it ourselves and when we move you can keep the treatments. You tell me where you can find tenants like that???
Now I'm talking just gay men here. We tried a few lesbian couples and we wound up calling the cops on them for beating the shit out of each other in the front yard every other day.
Sal