It's a bad dog that deserves not a crust.

A crust stands for a very small allowance. The saying suggests that a dog would have to be exceptionally bad to merit being denied even that much.

Applied to people, it argues against withholding every kindness or benefit because of someone’s faults. Even a modest share may be deserved unless there is a strong reason to refuse it.

Use the proverb when someone proposes denying a person even a small favor, share, or opportunity because of their shortcomings. It casts complete refusal as a severe judgment.