I try not to get too confrontational with most situations that I run into. I feel the need in cases like these is to stay your line and make them pass you.
However when i'm feeling argumentative I get in their way, make them stop and let 'em have it. It might not make them change their habits but at least I told 'em what was on my mind.

where I live only homeless people, crackheads, and newbie college kids ride on the wrong side of the road.