MMmmm. Theres 2 sides to this.
I was out on the bike one afternoon , indicating to turn right, moved over to the middle of the road , and had my arm out to signal turning right too, as I was about to turn, somebody in a car overtook me.
I was riding pillion with a mate whilst exiting a roundabout a woman in a mini who was indicating to turn left turned right across our exit. I went over the roof and landed on my head (no harm done there then) and my mate made a large dent in the side of the car.
I was riding around a roundabout and looking straight at me (always a dead giveaway that they haven't seen you)someone started to pull out in front of me so I headed to go around the back of him so he promptly stopped and blocked the roundabout completely. I was completely sideways when i stopped up against his door, twas a good job his window was up or i'd have throttled the sod.
When I'm out riding I generally assume that no one sees me and ride accordingly, even if i'm right in front of them with my indicators on and my arm out and my headlight on. I am far more alert on the bike than in a car, if you make **** up theres no cage to protect you. I've had one 60mph get off and a few slower ones, they tend to focus your attention. It seems to have worked so far, i've survived riding for 26 years.