Years ago the stacked tip-o-meter worked well, but today they do not get the tips alone they have to share so it does not have the same effect that it used to have, but it does feel good to take those dollars away.
In my profession I work for tips. Like any job it has it's good points and bad points. No customer has ever used the 'stacked tip-o-meter' on me. I would take it in stride and give the same impeccable service I strive to give however it would feel demeaning to me. You would feel the same if someone hired you and then said, "I'll be watching to see if you slip up, so I can deduct your pay." Don't forget that these same young people with no work ethic might also have no problem messing with the food they serve you. "Food" for thought.