Beggars can't be Choosers

Whats the difference between persistance and begging? I would think that persistance is when you are trying to repeatedly get something in order to reach a goal, and begging is when youre trying to get something you can't have or shouldnt be given. The thing is you can say the same thing vise-versa so in reality they can mean very much the same thing.

Begging however probably leads people to look a little less dignified. So when my friends ex is asking her to hang out over and over should he be praised for being persistant or looked at as pathetic for continually trying after she has told him 'no' more than once on the same day.

Its a fine line, between looking like a fool and looking determined. I guess it all depends on what you're going for and how you go about doing it.