We stayed in a hotel in Santiago in November and we paid cash in dollars so they didn't charge us the 19% tax (which also applies to card payments), but the whole idea is that the price in dollars should be cheaper than the price in Chilean pesos. What they might mean is that the price is 30,000 CLP which you pay in dollars at the day's exchange rate, and otherwise they charge you 55 USD, but that is still way more than 30,000 + tax. I would e-mail the refugio people to ask for clarification.

On a sidenote, Argentina has no black market rate anymore