This article is from the Stand-up Comedy FAQ, by Steven Rosenthal and Steve Silberberg (firstname.lastname@example.org) with numerous contributions by others.
A. Only to save yourself from stinking up a place. There are 2 types of
comedians. Ones that are in it just for the ego stroke they get from
audience laughter, and the other that wants to get a message across. It is
a rare individual that can do both well. Pandering to the audience will
help your ego, but won't help you develop as a professional.