it takes one bad apple to spoil the (whole) bunch

it takes one bad apple to spoil the (whole) bunch

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, it takes just one bad apple to spoil the bunch." I really loved my job, but there was this one jerk there who made life miserable for everyone. It takes one bad apple to spoil the whole bunch, unfortunately.
See also: apple, bad, bunch, one, spoil, take
Full browser ?