There's an old saying: When in doubt, don't.
If you buy and sell the chairs knowing that it's NEVER been intended to sell back an item for more than you paid for it (and come on, this has been around for the history of RPGs, let alone MMOs), then you're committing exploitative behavior. The extent of such behavior, of course, will be evaluated by BW but the fact remains: You're exploiting. Even more so if you choose not to heed the warning when you log in at this point.
Mistakes happen. Saying "nyaa nyaa, YOU made the mistake, so YOU deal with it" is simply attempting to rationalize behavior you know is wrong.
"Oh, you pulled an oopsy and left the bank vault unlocked, so why shouldn't I be allowed to just walk in and take as much as I want? It's YOUR fault for leaving the vault open like that!!"
No, just no. Doesn't work that way.