Personally, I just don't check out other guys in that way. Obviously, in locker rooms its pretty much impossible to not notice. I wouldn't say I treat a man any different based on his size, but I could see how it might be a thing for some people. I can't say that I've noticed straight men in the act of acknowledging my bulge either, though I have had straight acquaintances bring it up after the fact.
The few times I've noticed that my bulge has had an effect on the way people treat me is, I used to be in sales, and if a woman would notice it, the conversation usually gets a bit more flirty. Hanging out with my gay and non straight friends, it does get pointed out quite often though haha.