As the other reviews noted, they will try to charge you a tax ("impuesto") that does not exist. They tried to charge us over 20% of the cost of our meal as this tax. The food is terrible and expensive also. My coca tea consisted of hot water with a few dried coca leaves floating on it. Internet access is slow - it was what attracted us to sit down in the restaurant in the first place, not worth it. We did not find out about this tax until we sat down, got internet access, and saw the horrible reviews it received on Trip Advisor. That immediately put us on our guard. When the bill came, we refused to pay this extra charge and demanded that they give us a receipt with this tax shown with the rest of the charges of the food bill, so we can bring it to the tourist police to report them. They refused to write down this tax on the bill. We left without paying this ridiculous tax and went and found the tourist police. Unfortunately, they seem to shelter their own local businesses and were reluctant to do do anything about it. Overall, Aguas Calientes is a complete tourist trap - there is no good food anywhere, and the town will bore you to death. It solely exists because of the throngs of tourists visiting Machu Picchu and tries to take as much advantage of the tourists as it can. I say visit Machu Picchu and then leave. Spend as little time as you can in Aguas Calientes - it really is not worth wasting your breath on.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC