English to Arabic Other Idioms / Maxims / Sayings

The translation into Arabic of the phrase 'one bad apple' (as an abbreviation of 'One bad apple spoils the bunch') is needed for a poster about ethics, discouraging bad and unethical practices in business. The caption 'one bad apple' is placed on top of a picture representing apples.

As far as I know the closest Arabic equivalent for 'One bad apple spoils the bunch' is كل قرين بالمقارن يقتدي, but this will not work on a image representing apples.

I googled تفاحة فاسدة, and I had indeed many hits. I know this is a literal translation of the English idiom and that it is fairly used. However, I am not sure the Arab reader will understand the association and the meaning conveyed by both the image and the caption.

Any better/more creative ideas will be much appreciated.