I use self-promotion techniques that I know are more flair and feeling than rational points to convince people of how good I am at certain things; I then follow through by showing that I am, in fact, as good or better than my marketing material showed me to be. This combination works very well, and I do not feel deceptive for properly calibrating their expectations before I am able to provide true evidence.

I suppose I'm more concerned with how well they're calibrated (beliefs) than with their methods of calibration (rationality); the latter provides far more benefits, but is also far more difficult to change.