I was going to arbitrage XMR on Bithumb then I realized that BTC on Bithumb is $23500. 
The only effective arbitrage I can see here is via USD/KRW; however this must be heavily regulated in South Korea creating effective foreign exchange controls. Otherwise this arbitrage would have been done a long time ago. It is USD/KRW that is out of whack here.
Edit 1: The non KRW price should be considered the true free market price here.
Edit 2: If effective foreign exchange controls is not the issue, there is something seriously not right at Bithunb with KRW fiat withdrawals.
I certainly agree that we should not expect the Korean exchanges to be a good representative of the free market price.
On the other hand I have been noticing a tendency for some rallies to be frontrun a little by Korean action. However, this is more gut than due diligence.