As paid-up and dedicated MoFo's, we all oughtta dedicate ourselves to bringing back the "wave." Think of it as a freebie: just give to everyone--if they don't want it, fine. It doesn't cost you anything, and who knows? You might just get someone else started.
I pulled up on an old-school 1%er at a stoplight yesterday who was riding a very clean 1953 HD. Turns out he had no problem with my ride (of course, I led with a compliment on his), or, as far as I can tell, with me. My point is, you never can tell. I used to get pissed off at people who wouldn't dish it back--squids and cruisers. Now I just give it out equal-opportunity fashion.
That said, there is certainly a large minority of folks who seem to think that by buying a certain brand, they've bought their way into a club that need not deign to acknowledge fellow riders. Sad to say this goes as much for the over-refined beemer pilot as it does for the over-financed RUB and the under-IQ'd Dyna-glide-as-investment and GSXYZFTTSBK 19-35 set.
Anyway, the idea is that if you do it often enough, maybe they'll get the hint. Even if they don't, you can feel good about doing your part to create some solidarity among the brotherhood, and knowing something they don't: we're in this together.
See you on the street: I'll be the guy on a caffeinated '96 Sportster, waving at your a$$.