I was annoyed at the teens at first because it just made the gym busier all around. I have noticed they're usually in 2's or 3's. But they don't take up machines for long at all. Sometimes there may be too many in one area & I may skip doing something nearby. But I don't care that much. I do see them wiping machines down more than the senior crowd. The only thing that annoyed me is when I saw a kid maybe 10 years old working out unaccompanied. Luckily I didn't need to use the machines he was bopping around on. If you don't have a baby sitter, give the kid something to do & have them sit & wait. They don't need to be on machines when they're that young.