I ride my current ICE bike year round as long as there isn't ice on the rode and my work isn't closed. I wave at every bike I have time to and I have found those who also ride year round will always wave back. The summer / spring / fall squids who come out don't wave as often if at all.
By squids I don't mean squirrely-kid either, I mean those that don't wear all their gear, are seasonal riders, and are often found broken down on the side of the road because they don't keep up with maintence. This includes all types of subcategories of bikers in my book. Your perspective changes after you have been d own a couple times with full gear and you ride year round in all conditions when you look at other riders behaviors and 'gear' choices. lol
I should add my bike is a little unique. It is technically a ninja 250 but it has a huge touring shield on it, two v45's, a v46 with really annoying leds breaklights installed (all three cases on a wingrack which has a custom mounting solution built from aluminum and EMT), as well as sheet metal leg / foot guards in the winter along with hippo hands. So it kind of sticks out and screams "utility" from every angle and doesn't look pretty by any means.
That stated people who ride year round always wave back.
The pansies who ride seasonally and only if the weather is nice only wave back when their prejudice allows them.
Just my thoughts on this. I have only been riding for a little over two years and only have 38k miles under my belt so my observations might not be valid elsewhere.