What I run into is this: I'll be waiting in the right lane to go straight, and a car will pull up behind me. IF his blinker is on, I'll try to pull up and to the left enough to let him make the right on red. No blinker? I don't budge. I've considered a sign-language approach to asking whether they are turning but I think there's too much of a risk of miscommunication which would be worse than no communication at all in many cases. So I just watch for the blinker and leave it at that.