A few years ago, I was driving home from the gym at 6 PM. I came to a 4 way stop (Willow and Summer St in Acton) that I drove through/rode through almost daily. I was going straight across and a cyclist was opposite me, and I assumed he was going straight across, because he didn't signal or indicate otherwise. I almost had a heart attack, when he started to turn left in front of me, as I took off. I stopped, but I was badly shaken. He just assumed I knew he was turning... it could have been very ugly. As a cyclist, I was furious.
Although I don't live by there now, I do still ride through there frequently and one of my close friends lives down the street. I think about this every single time I go through that intersection.