It's not just hotels that do this - "Dynamic Currency Conversion" is very common in Europe (I'm UK based so my cards are GBP based).

It can sometimes, but rarely, be advantageous if your bank or card provider charge outrageous conversion fees but it's usually weighted in the retailers favour.

I have a credit card that charges no forex fees and gives me the interbank rate - so I keep a close eye out and demand to pay in local currency if this is ever done