It is common to respond to a person who is exhorting us to change our behavior by drawing attention to that person' s own behavior  This response, however, is irrational
Whether or not someone in fact heeds his or her own advice is irrelevant to whether that person' s advice should be heeded
We should not be too severe in our condemnation of the salesperson; we have all lied at one point or another. It is irrational to condemn a person for wrongs committed by everybody.