My worst/most annoying experience with a bible-thumper was with a Jehovah's Witness as well. It was a middle-aged lady dragging around her four or five year old daughter (as if to try and guilt trip the people whom they were harassing), and it was on the Sabbath nonetheless. She was passing around these pseudo-scientific pamphlets that tried to debunk the Theory of Evolution by saying, in short, that "Well, you scientist/atheist people can't completely explain the connection, species for species, between birds and dinosaurs because they have similar skeletal structures so God did it!" It had numerous examples in there; I remember a couple of species of fish, then jumping to a sperm whale. They had felines in it too.
I responded openly that I was an atheist and that I wasn't interested at all. I just took the pamphlet and gave her the typical politically correct "Sure. I'll try to make time and read it" bullshit. I remember I was trying to watch an Arsenal game.
Little did I know the crazy lady would return a week later. Funny part of it was, though, I unintentionally had my best atheist shirt on. It said "ATHEISM IS A NON-PROPHET ORGANIZATION" in huge bold font right across the front. I told her straight up that I didn't read it with the slightest bit of care and she never came back.