I define bullshit as self-interested talk, that uses both truth and lies. It doesn't have to be lie, it's just presenting truth and lies in order to manipulate the other. There is always something to gain for the bullshitter - money, relationships, advantages or to get out of obligations.
I think their definition of BS is in line with the academic literature on this, ie Frankfurt's seminal booklet (that the NYT had a hard time reviewing, because their editorial policy did not let them spell out what the whole book was about :-), namely statements that are not even concerned with truth, but just seek to impress.
I define bullshit as using big words and social proof, to present a conceptual theory (split) that might have some merit, but isn't particularly insightful.
