After learning about rapport, in retrospect I'm able to spot times when people that have intentionally built rapport with me by subtly mimicking my behaviors. The people who I suspect used it on me were: a hypnotist, 2 psychologists and a friend who is big into social engineering. I've observed the effect it has. Each time I develop a very positive view of the person and I fall under the assumption that they are a lot like me. Its hard to describe but its a very distinct phenomenon and easy to recognize once you've observed it a few times. By paying close attention I can spot my friend doing it to me, when I intentionally alter my behavior in a certain way I can see him subtly adapting to this new behavior I'm displaying.