Men say what they mean and mean what they say.
Women tend to talk in layers. They mean all sorts of things that bear no apparent resemblance to what they say (the literal words), and they sometimes say the exact opposite of what they mean.
This fundamental difference in approach to communication is a primary source of confusion among men and women, especially those in their teens and early 20s. Women think men should be able to follow all the layers, which leads to such fun statements as "well if you can't figure it out, I'm certainly not going to tell you!" Men meanwhile protest that they can't read minds.
There's also the classic case of the question with no correct answers. For example: "Do you think I'm too fat?" "Yes" is obviously wrong. "No" is wrong because "well he's supposed to say that" which means it really means "yes," which is of course wrong. Failure to respond is taken as "he's ignoring me! (he must mean yes!)" Sometimes the poor guy really does mean "no." o.O
I've found that the best first step in resolving an argument is to convince the woman that men are dense. This is not to say that I think men are actually dense, mind you - it's just a necessary precursor concept for the woman before she can grok how men think. Then it's a matter of redefining "politeness" and "directness" to not be quite so much at odds.
(As with every post I make relating to gender, I'm aware that a whole bunch of you are thinking "oh yeah? well I'm not like that at all and neither are any of my friends!" Well. I can only say the same thing I say every other time - there's a reason why these stereotypes exist even if no one you know is a good example of their raison d'être.)