one bad apple spoils the (whole) barrel(redirected from one bad apple can spoil the barrel)
one bad apple spoils the (whole) barrel
It only takes one person, thing, element, etc., to ruin the entire group, situation, project, etc. Refers to the fact that a rotting apple can cause other apples in close proximity to begin to rot as well. A: "It used to be considered the top research facility in the region, but after one of its researchers was discovered to have plagiarized a number of his papers, the whole department's reputation has been dragged through the mud." B: "Well, just one bad apple spoils the barrel." I really loved my job, but there was this one jerk there who made life miserable for everyone. One bad apple spoils the whole barrel, unfortunately.