If you're a hotel dealing with one unhappy customer you only stand to lose the future business of that customer, and any negative PR (usually non-existent) that they can personally inflict upon you.

When you're dealing with a customer you get through a lucrative distribution channel you're liable to lose your standing on the distribution channel as a whole.

Negative reviews by that customer and customer service load on the distribution channel caused by you will impact your future business as a whole. This is true for all major distribution channels that I know of, such as Amazon.com, eBay and various OTA's.