Boundaries, and that it's okay to have reasonable expectations of the people we live and work with.

And no, you are not an idiot. Rather, you are probably a very good person in situations where other people don't behave so well.

Where the real issues lie is in the 'why.'. Like the guy at the office with the coffee- does that thing not bother him, and he thinks nothing of it, did no one ever teach him, or does he feel entitled to leave a mess to be cleaned up by others?

I'm always striving to have more effective communication in situations like these, but in reality, it can fall of deaf or assinine ears. But at least we can say our piece.

Like the guy with the coffee, I might have said something to the effect of, "oh, let me get out of your way so you can rinse the sink down." A conscientious person would probably be slightly embarrassed that they didn't wait and do that. Then he would wait for you to move, and rinse the sink.

A self absorbed person would probably tell you it's no big deal and leave, but he might take more care in the future.

A passive aggressive person will start dumping the coffee in the sink in a way that makes an even bigger mess, just to get even with you.

So, you have a right to nicely state a preference, but how they react is going to tell you exactly who they are. But if you don't say anything, they will never know and we can't expect changes. If they don't change, well, that's on them.

It's a good question though, because I bet most people can relate to someone they deal with who doesn't have the consideration for others that they should in a given situation.