An additional sign of character is to see how they treat people who are less fortunate or in lesser social stature and may not be able do something significant for a person. Example how they treat waiters, chauffer, doorman, busboys , old people noisy children etc.

The greatest sign is to see what someone does when no one is watching or when they are able to hide their identity (writing nasty comments on the internet forums for example). But these are difficult to trace.