I truly wish I was on the other bus; the amount of attention I've had off gay guys, as compared to that I've had off straight women, is bemusing in the extreme.
During my first year, I was totally wasted, on a student night, and got talking to an older, gay student; I don't know how, but he ended up spending the night in my bed, trying to **** me off and snog me, at one point. The best possible explanation I can come up with is that he suggested coming back to my halls for some drink etc, and then ended up climbing into my bed, after I'd passed out, and the next thing I knew, he was trying to take things one step further.
Then, also in halls, there was the guy I made friends with, who came back to my room for more drink, collapsed on my floor, before then later taking it upon himself to clamber into my bed; had I not been so paralytic, I'd have kicked up something of a fuss. Fortunately, he was more recently out of the closet than the previous offender, and did nothing more than plant an affectionate kiss on my cheek.
Then, there was the guy I met in a park, who invited me back to his, 'for a beer'. Being pissed, I accepted, only to have him put on a video and begin masturbating, before asking me for "a hand", and urging me to let him give me a hand, also; there then followed one of my swiftest ever exits. I bumped into this guy again, a few months later, but was this time wise enough to make an excuse and walk off quickly, when he attempted to lure me back once more.
Then, there was an aged Norwegian guy who started talking to me outside a cafe, coming across as a genuine, innocent-minded tourist, until his mention of a proposed visit to a gay club; immediately, I knew where things were going. However, in broad daylight and public, the furthest things went was comments such as "If I'd known you existed, I could have booked a hotel room with a double bed", "Have you got a girlfriend? Boyfriend?", and "I'm having a good holiday, but it would be better if you were a bigger part of it". Still, he handed me a £10 note, for the hour of my time he took talking to me; one can only imagine how much I could've earned, were I to have agreed to acts of buggery. He invited me back to the same spot, the following day, offering me the chance of a free lunch; it wasn't the thought of lunch that deterred me from accepting his offer, but more what he would have wanted for dessert.
Then, there was the guy in a (very straight) club, who started asking if I was gay, and initiating a snog with me; fortunately, I was sober enough to make my sexuality clear, and to fend him off, this time.
And then, there was a guy who was part of a group I got talking with, after a night out, who started asking me to sit on his lap and to take my top off, complimenting me on my body and asking if he could **** me off; I was jokingly going along with it, until the last request.
All these occurences, in a short space of time, and my only 'crime' is wearing a leather jacket. I can only think that it's down to my politeness and friendliness, on each occasion. I suppose that blokes tend to be super-horny and forward, most of the time, and that maybe this stretches to gay blokes; but then, being as they're feminine, does it? Maybe I'm just gay icon material? Either way, I've been approached more times than blokes, than I have women, and I've never even been in a gay club in my life.
So, yeah, I can identify with your plight, 'OP', that's for sure. Being as you, however, actually were in a gay club, the two gays who hit on you would have reason to assume you were gay, so I wouldn't worry as to your potential campness levels; you wouldn't need to be camp, for them to make an assumption, given the circumstances. As regards your other experience, well, I can't help thinking I'm strangely far more attractive in the eyes of gays, than I am in the eyes of women (actually, when I did go into a gay pub, once, with two (straight, female) friends, I also had one guy say he liked me, after I left), so maybe the two groups do go for different types; probably more promising than not being attractive to either types, though, as I'm sure there's some correlation present, between how attractive gays and girls find certain guys.
If you're shy, this probably explains a lot; while women tend to prefer confident guys (and shy guys find it difficult to approach women, and hence don't tend to have much luck with them, which may be your problem), gays often prefer shy guys, and probably see them as less intimidating than some guys (who may be homophobic), and as more likely to be gay, being as gay guys are often shy. I probably came across as quiet, in many of the above situations, which may go some way to explaining them. Chances are you're attractive to women, as well, but your shyness holds you back in this respect, one way or another, but doesn't when it comes to receiving homosexual attention.
I suppose it's good to know that, if things get bad enough, we can always become rent boys. Only joking.