I am guilty of wing waggling, sometimes quite deliberately. When flying non-radio it feels friendly and in any case it adds, maybe, to ones conspicuity.
I can count on one hand the number of times such a gesture has been reciprocated. A particularly stunning sumer evening, shared locally with a balloon, was the last occasion when I can recall that emotional glow from the fellowship of the sky.
No, the balloon pilot didn't quite sprout wings, but we understood each other (I think...)
I've come over all purply, now....