I don't know whether it has anything to do with the leather scene being integrated into a lot of the gay/lesbian social scene but there does seem to be a little more openness in the LGBT community to the 'little signs' and I'm not just talking about bringing your date to functions on a leash.

I think delia is right that you can develop a sort of gaydar for D/s over time. Of course, the amount of time that is invested in developing your skills at detection is in direct proportion to how hard you are looking for someone to play with--I know when I'm happy and settled, I'm oblivious to the signs but am quite keen when single and alone.

I had to evacuate from New Orleans (a very open and welcoming city) following Hurricane Katrina to a small town in southern Alabama. Once there, I was desperate for any sign or symbol of alternative sexuality. I was almost giddy one afternoon when I spied the trinity bdsm symbol as a static cling sticker on a car. Had I not been out with my Mother, I would have camped out by the car until the owners returned.