I don't... I always say thank you. But then again, I hold door's open for some women and it's not often they acknowledge with a thank you, I just say 'oh your welcome' in a loud voice
I was at that very spot a few weeks ago and managed to clear all our rubbish. Bins in the park were full so I just chucked it the boot of the car and binned it when I got home, why is this beyond some people?! Pisses me off too!