Suspecting something, he added: "When you are finished, don't forget to pull the chain. See. That's what the sign says." And, to
be sure, there was a paper with writing tacked to the wall, next to an aluminum up-and-down pipe. The hotel clerk most likely suspects that Ernesto and his mother do not notice the sign on the wall. have to go to the bathroom right away. do not understand what the sign says. think flushing a toilet is a waste of water.
From the excerpt, the hotel clerk is suspicious of something and he tells Ernesto and his mother that when they are done, they should not "forget to pull the chain" and so he is sure that they understand what he is saying, he shows them that it is what the sign says.
So, from these series of actions, we can infer that the hotel clerk likely suspects that Ernesto and his mother do not understand what the sign says.
