no (person) worth their salt would (do something)

No person who warrants respect in a certain field or profession would engage in such bad behavior or activity. No professor worth their salt would remove a student from class just for asking controversial questions. It's baffling—no doctor worth their salt would have missed such an obvious diagnosis.

no teacher/actor, etc. worth their salt

COMMON If you say, for example, that no teacher worth their salt or no actor worth their salt would do a particular thing, you mean that no teacher or actor who was good at their job would consider doing that thing. No racing driver worth his salt gets too sentimental about his cars. No player worth his salt wants to play in the lower divisions. Note: Instead of no, you can use any or every with this expression. For example, if you say that any teacher worth their salt would do a particular thing, you mean that any teacher who was good at their job would do that thing. Any policeman worth his salt would have made proper checks to find out exactly who this man was. Every teacher worth their salt will learn as much from their students as their students learn from them. Note: In the past, salt was expensive and rare. Roman soldiers were paid a `salarium' or salt money, so they could buy salt and stay healthy.