Sometimes I wonder how many times a woman has started a conversation hoping I would flirt with them and then realizing that I'm way too dense for that.
I'm reliably informed that it's a non-zero number but I'm too clueless to manage a guess at the number.
@Blenster in university a woman tried to strike up a conversation with me using the line "I think we're in the same class". I did not recognize her and I said "no, I don't think so", and I went on my way. So, same!