various responses

"Hey, do you know if Joe is in with Schmoe?"

Now, what answer do you give here? Yes, you know that Joe is in with Schmoe. So you say yes.

Then, person asking the question takes off, mumbling that ok, Joe is in with Schmoe.

However, that is not what you were saying. You were simply saying you knew the answer to the question of whether or not Joe was in with Schmoe.

Along the same lines - "Is Joe around?"

Yes, Joe is around. Is he available is really what you want to know, so when I say yes, he's around, and then you ask to talk to him and I say he's not available, you're a little perturbed that you went through that and I said yes he's around...

Ask the question you really want the answer to people. Think about it just a second more and be real.