I like my approach. Depending on how much of a mischevious mood I'm in, I eye up the prospective candidate first to see how unlikely a response is. Then, as I pass I will shout a greeting of somekind, like "ello mate, how you doin', or how's the wife?" Loud enough for it not to be ignored. Kind of forces a reply of some sort followed by a bemused look as if they should know me. If there's no respnse, I'll usually try it a little louder! A kind wave as we pass by usually adds to their confusion. Just to add, it doesn't work through matches.
Keeps me amused.
My particular favourite was at the winding hole south of Nantwich. A portly pair in electric mobility chairs were fishing right slap bang in the middle. As I got ready to turn the male shouted to me "oi, isn't it wide enough mate". I said yes, quite, that's because it's where we turn the boats! I was slightly distracted so had to turn a bit quicker than anticipated with a lot more throttle on than usual. I'm not sure of how much of my wake they got to suck!
They didn't respond to my fond farewells.