Damn late on this thread.
No I don't give money out to them if they ask/just sit there. The ones I've seen all look able.
I give out to performers though, i.e. music ones/singing and more if it's more unique (what do you call them live statues? I always admired them), live statues/animal shows, etc, they're the cool ones.
And although I've always avoided them, I find "The Big Issue" sellers are always polite and friendly, but I've never brought off them before (legit homeless/poor people working by standing at popular/busy spots selling "The Big issue" magazine, which is basically written by the same people).
XI Wiki


