I see trainers having their client performing a set of a given exercise, while they are texting on the cell, neglecting their client's safety.
Walking all the time while training a client and holding a large cup of I do not know what in a way where they are flexing their biceps. It looks like a 1 entire hour "static contraction" of a hammer bicep curl repetition.
Trainers doing the same training routine for all their clients.
Trainers using a piece of equipment, while they leave a towel on another piece of equipment as if no one can use it.
These are few common scenarios I see every time I go workout.