I have encountered what the OP is talking about. I understand fees that hotels have are not included like a resort fee, internet access fee, parking fee, etc. I understand those and they are quite common at hotels (especially 4-star ones) and it comes with the territory. However, what the OP encountered and I also did at the America's Best Value Inn near Dollywood in Pigeon Forge, Tennessee is another story. When I checked in they tried to charge me about $12 as a Hotwire Customer Fee. This fee put the rate I paid up to the advertised rate that was on their sign outside the hotel. When we complained to the hotel the manager said that in order to stay in business he had to make up for the fee that Hotwire takes from the booking and that he doesn't get. I tried to explain that that was a cost of doing business but it was like talking to a wall. I went on to call Hotwire Customer Service and they were very apologetic and called the hotel to find out more details. The hotel told them the same line they told me and Hotwire informed them they could not do that. Since it was peak season and we needed a room, I paid the fee, but Hotwire refunded it in the end. So, outside of the normal fees that hotels charge - for specific services - if the hotel tries to charge you a "customer fee" or whatever, make sure to call customer service as they are not allowed to do that.