The worst part of the practice is it is often unclear what their intentions are. Are they waving to me? Are they gesticulating to a passenger? Are they swatting at a fly?
I usually don’t consider that they are luring me into a trap but I suppose thinking like that can keep you alive on a bike.
I have actually heard people shifting into reverse when I go behind their cars. however, that leaves enough time time to dodge and eliminate any plausible deniability.