The rotten apple spoils his companion
I don't think that means what you think it means.
Rotten Apple
Please remind the people who say, "there are only a few bad apples," or "there's always going to be a few bad apples," it doesn't work that way.
These folks should learn the full proverbs:
"As one bad apple spoils the others, so you must show no quarter to sin or sinners."
"A bad apple spoils the bin,"
Benjamin Franklin had it as "the rotten apple spoils his companion," which goes back to Shakespeare's time.