In the scene where Matthew Perry just vomited and Natasha Henstridge enters his hotel room, carefully watch the bottle of, I believe green, mouth wash on the left side on the screen. Then it's there and then it's gone...
After he returns to his meeting, he goes in to vomit. The sink was empty when he went in. After speaking to Cynthia, he returns to brush his teeth. Everything has been setup for him as if someone else did it. When he finishes, the sink is empty once again.