Rather than assume you have been seen, assume they will do the worst possible thing at the worst possible time? I learned to slow down and cover the brakes on my motorcycle in these situations, right of way be damned. But you can never be 100% perfect, nor 100% clairvoyant, so panic braking and panic swerving are excellent skills to have at your disposal.

Like the time I was teaching a co-worker and new commuter about staying three feet from a line of parked cars, and not more than three seconds after I finished speaking out pops a car door in front of us, and I was a tad too close in anticipation of making a right turn. I had just enough time and room to swerve, and the coincidence had us laughing for half a mile.