I’ve found that people tend to respond to your expectations of them. If you treat them in a way that shows you have confidence that they’ll behave honorably, they will usually be reluctant to betray that confidence. If they sense that you are dubious about whether they’ll do the right thing, then they will feel less concern about their image in your eyes.
There was an interesting study about the effects of publicity in influencing public behaviors. It found that PSAs shown on TV back in the ‘70s that showed littered landscapes bringing a tear to an Indian’s eye (I remember those) actually had the perverse effect of making people more inclined to litter, not less. This was because it sent the subliminal message that lots of people litter, so that it’s a more or less expected behavior. It’s more effective to send the message that good behavior is the norm, so don’t be that guy .
In my interactions with people on Fluther, I try to respond to things people say in a way that shows that I haven’t written them off as decent, well-meaning citizens of the tide pool. That may mean just letting some sharp remark slide on by, counting it as a miscommunication rather than a personal affront. It always means abstaining from ridicule and insult; as good as it may feel to deliver a good burn, it clearly signals to your target that you have no esteem for them, and they will feel no compunctions at all about behaving like an asshole toward you. It may mean taking a deep breath and reaching out a hand of friendship—adding them to your fluther or sending a positive PM, for instance—to someone you’ve had some conflict with. I’ve seen that completely transform the way someone interacts with me.