I own an insurance agency. We have a few dozen workers and it’s a great business, so every so often we have to hire more people. Sometimes, when all I need is another secretary or bookkeeper, I’ll hire girls just out of seminary. After interviewing them, I call them in for a few days on the job. They come in for 4 hours at a time, during which one of my regular workers takes time off from her regular work to train the new girl. They have to be taught how to answer phones, keep logs, update calendars and other jobs. If the girl is good and we want her to stay, we pay her from the first day that she came in, even though it was only on trial basis. But if we don’t, and let her go, are we obligated to pay her? Usually, if we let a girl go it is because she is incompetent, lacks basic skill or just a waste of time. May times I lose from having the regular worker spend the day with her instead of doing her regular work. So what is the din, rabbi. To pay or not to pay?
Halachically speaking one does not have to pay a worker who did not do his job, when the reason for the unsatisfactory work depends upon the employee and not the employer. Nevertheless, if it accepted in your country or your field to pay such workers, she must be paid although her job was just a waste of time.
See Nesivos 335:3 regarding a worker whose work was useless.
See Iggros Moshe Choshen Mishpat part 1, chapter 76 regarding the accepted practice in a workplace.