I don't deal with them, I avoid them at all costs
I hurt them by playing by their own rules.
I just ignore them.
It's difficult and draining because they take advantage of your kindness and to me that's not right.
First of all, by seeing where they're coming from and communicating from there. In the few instances where that has failed, I just got on with what had to be done, no harm intended.
pity them and use them for entertainment