I see a few cyclists touring through my home town. I usually try to strike up a conversation, which usually leads to an invitation to stay at the house. (It helps being a Warmshowers host with good references.) A couple of times I've gotten a surly reply like Yul Brynner's character, and I just leave them alone.
My point is that there are friendly honest people out there and you need to be receptive in order to meet them. It's a risk, sure, but in my mind that's what bicycle touring, and bicycling itself, is all about. It can be a little riskier at times than car travel, and that's why I do it. Who wants a life with no risk?
I consider myself a social cyclist. Interaction with locals, from a friendly wave, to a shared picnic, to an impromptu overnight stay (or even lifelong friendship in one case), is a major part of my travel. But I've traveled with people who make me look shy. And it is possible to overdo it, I think.
Along those lines, I think your character actually influences how motorists treat you on the road. I meet aggressive road cyclists who complain about all the negative interactions and close calls they have. I hardly ever get those. I estimate one out of 10,000 motorists are just jerks, not a bad ratio and worth the risk for me. But I use a mirror all the time, and often just get off the road if I see a close call coming--it's not hard to spot inattentive or aggressive drivers. I always obey traffic signals (well, when a motorist can see me). I always smile and wave when one yields to me. I avoid conflicts because you just don't win them on a bike.
Just the other day a woman in a car stopped next to me at a traffic light rolled down her window and chatted a bit. She thanked me for being visible and careful. That was nice, and I think she might even ride her bike next time.