Sure, no problems, whatever you want

We don't mean what we say, nor do we say what we mean.

That is a basic feature of communication that is usually unnoticed. It is related to the fact that there is no unique definition of the concepts we use in language, and to the way we communicate on many layers all at once. Nothing we say simply conveys a message relating to the context of the sentence we speak, but it always includes something of our mental condition at the moment in which it is uttered, the relation to the listener and other features of the context.
For instance, say you wish to borrow a book of mine. Albeit my lack of attachment to private property, it is possible that you know that regarding my books I display all those primordial tendencies that possession can arouse. Say the conversation goes like this:

"Can you borrow your copy of Hitchhiker's Guide to the Galaxy?"
"Sure, just make sure you bring it back."
"Oh yeah, no problem. Of course I will bring it back."
"Great, then you can have it."
"Thanks. (pause) You're sure it's alright?"
"Yeah, sure. (pause) Just make sure you bring it back."

I take it that you agree that this conversation seems reasonable, though if we only said what we mean and meant what we say, it would probably take the following form:

"Can I borrow your copy of HHGTTG?"
"Yes, provided you give it back."
End of conversation.

The second conversation covers just the same amount of 'meaning', conceived in a narrow sense of references, as the first one. However, the second conversation misses the richness of communication encapsulated in the seemingly redundant repetition of the first, likely conversation. In addition to asking the book from me, you want to know my attitude towards the book or books generally, as to make sure that I mean what I say when I say you can have it. You would be happiest if I just replied enthusiastically "Sure! You can have it for as long as you want!", which would seem strange despite the joy I take in the spreading of a good piece of writing. I, on the other hand, would like to convey the message that I am happy to lend the book provided you give it back. I don't want to make a big deal out of it, but I do want to make sure that you know that even though I have not opened this book for years I would really be upset if you failed to give it back and it would be missing from my library.
Making sure we understand each other is an important feature of communication.

Ironically, it usually entails repeating points we have already made rather than making new ones.

Some Things Are Better Left Unsaid

Here is my greatest fear:
To feel good around people who actually don't welcome your company and wish you would go away. Their problem is that they can't tell you to go away because their problem with you is exactly that - you don't seem to understand yourself that your presence is undesired.
This situation, I think, is not wildly uncommon. Many of our social norms are based on unspoken communication and implied agreements. If you are talking to me and I am slow to respond, I am busy. It's not that I'm not interested to hear what you have to say - I'm just focusing on something else. If you keep talking to me, I might just tell you that I'm busy right now and will talk to you later. I will be slightly annoyed when I do this, even though I will probably apologize, since you should have known.
Very few people will stay in the room after a direct reproach and repeated requests for their departure from an otherwise ignoring person. Those who stay in the face of such severe reactions from the environment are indeed very lacking in social skills and would probably use some help from those who care about them and have had good experience interacting with human beings.
We all fail, now and then, in interpreting the unspoken gestures of our friends and neighbors. But the person who gets them systemically wrong is one that lies beyond the reach of our rebuke. If you ask them, at any particular point, to leave or stop doing something you've been insinuating is annoying - they will simply stop, in deference to your request. Your frustration, surely to surface after keeping quite for so long, will only perplex them: if that was bothering you, why didn't you say so? A way to deal with such a person is to constantly tell them what is usually left unsaid, for good reasons. That is not only extremely tiring but could also drive a relatively stable human being fabulously mad. The usual way to cope with such behaviour is to grind one's teeth and pray to whatever god that happens to be available that the awkward person just go away.
The two-sided predicament is not something strange to me. Many times I have been on one side of it. Was I ever on the other side? I don't know, I'm afraid.
And when I say that I'm afraid, what I mean is that I'm completely horrified by the thought.