Imagine you are driving down a city street and there are a line of parked cars to your left. Suddenly, without signaling, one driver zooms out of his or her parking spot and cuts you off.
Can this be avoided? If they didn't signal, it's difficult to avoid it, but it's not impossible. Here's how: If there are parked cars on the side of the road, watch for the shape of a driver's head above the driver's seat. If you see someone's head, there's someone in that car. It doesn't necessarily mean they are going to zip out in front of you, but at least you know there's someone IN that car and they could be thinking about leaving their parking spot.
Slow down slightly and, if there's room, move closer to the center line to give yourself a little more space to maneuver if someone does pull out in front of you.
