I suspect we are dealing with two populations here: those who think bullshit is a valid mode of argumentation, and those who know it is not, but use it anyway. Those in the latter category know that their bullshit can be called, so they are only likely to use it when they are fairly confident that it will not be recognized as such by their target audience, or when they consider the stakes justify the risk.

Politicians and political commentators, trial lawyers and PR flacks come to mind.