And why do people do it?
Basically, people on the PC think they're a bunch of little detectives and most UC traders won't trade for pets without a cache/with a suspicious one.
Same goes for if you just have UCs on an account and you plan to be board-active--doesn't matter if you're trying to trade. People get snoopy.
That guide is great for explaining it further, though. c: I'm no expert, myself. I'll have to take a look!