When you gossip about another person, listeners unconsciously associate you with the characteristics you are describing, ultimately leading to those characteristics' being transferred to you. So, say positive and pleasant things about friends and colleagues, and you are seen as a nice person. In contrast, constantly complain about their failings, and people will unconsciously apply the negative traits and incompetence to you.

59 Seconds: Think a Little, Change a Lot (ed. Anchor, 2009) - ISBN: 9780307593269