回复：那就直接告诉他，要等到房子弄干净后才能退回差价，不会超过21天。

That's exactly what I told them 1 week after they moved out as they kept pressing me to send refund check since moving out.

My original subject may be a bit misleading. I didn't mean to ask if you think they are "极品" although I think so. What I meant to ask is if "filing police report" for this kind of matter is against the law; I don't know if they did so, though.

Being a landlord is sometimes tiring; but having a chance to see human natures of many who otherwise are complete stranger to my life is priceless...