And that has been going on since vanilla, That basicly what "Global" chatt is for.
Look, If you make a guild or a raid you want a lot of people to come fill it, a lot of people hang on global to find stuff, get it? its pretty simple.
If you sell a character you don't look for "a lot" of people, you only want 1, and that 1 person is so rare to find that you have to spam global for days, instead of maybe 1 hour to fill your group, do you get the huge difference now?
If blizzard would introduce "character selling" like warmane did, and not implement a restriction on global chatt, how do you think global chatt would have looked like in retail? in all seriousness it would be a F**king mess, Just like here.
What it boils down to is just how long and hard the staff is going to turn a blind eye to this problem.