Sending clear signals

I read a lot of science fiction. This year I read two different book series that describe societies where your relationship status, interest in finding someone, what you are looking for, what type of person you are, etc. are clearly shown by what you wear. In the one case it was jewelry and in the other it was clothing style and color. It would be really nice if people could send such clear signals. Knowing that someone was approachable or wanted to be left alone would make life so much easier.

Of course people would abuse it and lie, just like they always do. But I really like the idea of societies that tell the truth and that send clear signals.