Backfired Plans

So I attempted Marianne's challenge to meet and interact with people. Last night I went for a cup of Chai at my favorite local coffee shop. It's a mom and pop kind of place, usually filled to the brim with college students from UTEP. Armed with my classic Coach tote, an issue of Cosmo, and not much else - I sat down to read and watch Monday night football on the plasma TV. The owner attends my church and we had a nice little chat. Then a man who looked at least 45 approached me. At first, I thought he just wanted to take one of the chairs at my table. But that's not what he wanted. The guy introduced himself and asked me "if I wanted to have a conversation." I told him I was a bit busy.. trying to decline. For the rest of the time there, I couldn't bear myself to look in his direction. He was playing chess by himself? So he's old enough to be my father, not attractive, and had an accent that I had an extremely difficult time understanding. Not that I mean to be rude, but I feel utterly uncomfortable around men that I have no interest in - but like me. Does that make sense? If he were closer to my age I might have been flattered. But with this person - just creeped out. Why is he hitting on someone half his age? Is this bitchy behavior? I'm not quite sure. I feel guilty turning down guys sometimes, but they're all males that are totally unappealing to me.
I don't want to date a man if I am positive that there wouldn't be any sparks on my end. In the long run, they're better off not being lead on to think that I'm interested. Where can we draw the line between having realistic standards and being overly picky?? I honestly don't feel I hold men to impossibly high standards, but I'm beginning to wonder why I never have mutual feelings for my 'admirers.' Am I attracting the wrong kind of males, or am I attracted to all the wrong ones?