First of all, their motive is primarily cost savings rather than environmental, which is fine -- I want lower hotel costs too. If they asked me to reuse the towel to reduce costs, I could respect that and would likely comply. They are using the guilt many people harbour about the environment to get what they want. Just be honest.

Secondly, the "majority of guests ..." is a blatant example of argumentum ad populum, a logical fallacy. Appeal to me based on my self-interest, appeal to me based on the environment -- I may or may not agree -- but simply stating what other people are doing is not sufficient. I disagree with a lot of what other people do. Also, devices like "in your specific room" are transparent and annoying. If I checked-in to a particular room where, by sheer chance, the last 200 people trashed it, would it be then OK to do the same? That's the same argument they're using.

Oh, and one small thing, they're claiming to know why the previous guests picked up their towels up, and therefore to be mind readers since there was no survey. They can't say "well, that's the popular opinion" because they're talking about that specific room.