He waits it out, going and half-raising a folded wing so he can wipe his beak on what's left of his hand. "Well, I'm saying it now. People as a rule don't like having their shitting habits questioned." He isn't usually that vulgar, saying it like that makes his inner eyelids just barely show. Asking about, well, bathing and grooming could fall under 'bathroom', though, and that's less of a faux pas. "It's also why you don't stand right next to someone at a urinal."

'Vandalizing', huh? He'll have to remember that way of putting it when people get around to asking. They will. People don't have high opinions of pigeons.