Hah. I am always amused to see a back-quake coming my way-- I usually mutter some swear words but I am still amusedAnd yes, it usually involves another WOZ member, probably because (a) most good wipers are here, and you have to be good to use back-quakes effectively; and (b) casual wipers are probably unaware that you can backwards quake.
I don't think I have done any myself, yet, because the only times so far that I could successfully pull it off would be against n00bs-- and it seems too cruel to back-quake somebody that can't even fly their ship straight. Sometime I will try it against some of y'all even if it means I loose the race!