I know you say you're 99pct straight, but come on, a guy who's a member of LPSG and posts his cock on the web is very likely NOT 99pct gay. My guess is that something in that, er, "1 percent" of yours is sending out some pretty serious gaydar.
But maybe these people are at least partly right... about both of us.
Good luck.
As I read this thread I think that swimersox may be on to something here. Let me guess that good looking but completely straight guys don't even notice that other guys are checking them out, if they do. They don't return smiles with smiles, they don't show off for guys nearby. Their attention is on attracting girls whom they can bed. If some guy actually hits on them, the response they get is immediate and clear signal of either disinterest or a look easily interpreted as a warning.
What I read says you do neither, but, instead, are open to the communication. Others are watching, and see that. They may interpret that acceptance as an invitation.
So, thinking again of swimmersox comment, something important may be going on in that one percent.