I'm pretty sure that Rowling is doing this deliberately, just often enough to keep the pot simmering nicely.
Well that's open to debate. Apparently, David Yates, the director of the fifth Potter movie, was clued in first. He had tried to include a line in which Dumbledore refers to a past romance with a girl in the script, just to make his character a bit more interesting. JKR had to step in and tell him that DD didn't really swing that way, sorry.
And you're right, Ann. I'm sure that was what Roy intended. People are just pervy, what can you do?
And FYI, Harry/Draco is one of my all-time favourite pairings. Some of the best fanfiction I've read has been written about them. It's amazing how well they work together, really.