I just read a short story by Daphne du Maurier called Blue Lenses. [Minor Spoiler.] In the story, the main character is in the hospital getting fitted for a pair of eye lenses. They turn out to have a strange, and often disturbing, side-effect: they reveal the true nature of person she is looking at. [I won't say more than that, because that would make it a Big Spoiler.]
It got me thinking. What if a person's true sexual nature was visible to anyone who looked at him or her? If you could know at a glance if a person's desires matched you own? Would it make for more happy encounters? Or would it just be weird? Would people assume just because you were into spanking that you were up for being spanked by anyone at any time? It seems like there would be some possible complications!
On the other hand, I went to a spanking party once, and we wore color-coded name tags--names in blue for spankers, names in red for spankees, names in orange for switches. At the party, it made things a bit easier to negotiate, and there weren't any assumptions made.
So would you like to know? Maybe there's someone out there you never though was into spanking and if you suddenly had a way of finding out...