Politely Said But Not Meant

I know people say things they don't mean. I say excuse me as I push through a crowded hall with my arms full of stuff, and what I really want to say is, "I'm in a hurry, and I'm carrying this heavy stuff, get the hell out of the way." But I don't, that's not the polite thing to do. But lately I've wondered, when is it not polite to say things you don't really mean? When do you cross the line, when do feelings get hurt, when do you know when the person you say it to thinks your completely full of shit, and not being meaningful?

He says to her, "Don't give up on us, I don't want you to give up on us."
What she hears is, I can tell you are starting to lose interest, and I want to keep you around just in case I decide this is what I want.

Hey says to her, "I did just get out of a serious relationship, but I've already had a rebound, let me take you out sometime."
What she hears is, I want in your pants.

He says to her, "I'm just not feeling it."
What she hears is, I miss my ex, and I really think I've got to try to get her back.

He says to her, "You are so sweet and beautiful, but you aren't a girly girl at all, I like that."
What she hears is, I've got to play this just right, she's independent and I think she will fall for this non-girly girl crap.

He says to her, "I don't want any competition, just me and you."
What she hears is, I'm to lazy to show you I care, so I'm just going to make you understand that I'm not going to put in the effort.

She politely listens to it all, everything they say, but she hears the truth in it. She knows when it's not meant.