What else did you do in the bath you dirty fucker.

The thing is that on some level it annoys you as otherwise you wouldn't react by deleting their number. In fact deleting their number sounds like a way of dealing with the rejection, which is fine - it's a great way of forgetting about it. It's not that different a feeling from one-itis, which most say you should solve by going out and meeting someone else. You simply replace the emotion or any time you have invested.

Do you really think the girls who put up with it from you are idiots? The whole reason you do it is to get attraction from them on some level - it seems harsh to call them idiots afterwards.