Yes you do. If you're stopped at a red light far to the right, and an SUV pulls up next to you - maybe or maybe not making a right-hand turn - it's time to care what a motorist thinks. I'm trying to outguess these people all the time and do every thing I can to "care" what they're thinking! If you live in a town where motorists look down on cyclists, then you may need to ride differently based on what they think. In El Paso, I am pretty much invisible to cars, because we are not a bicycle city - therefore I ride side streets more than main streets (generally). I'm suggesting that if you really don't care what they think, it might be time to start.