1) Profound favouritism - you can actually be unintelligent as long as the right person(s) like you
2) Senior management consistently speaks poorly of clients even when clients make perfectly sensible requests
As an example of the culture at Analysis Group, in one office of 25 people, all consultants and their +1s were invited to the firm's holiday party except for the receptionist. The reason given was because she had only started 2 months prior. (By the way, they made this person send out all the invites and organise logistics.)