I've never met a pro police type that would mention anything as corruption. If you asked them directly some would agree, but as a group I generally just hear apoligism.
How can it be corruption when it's all because of just "a few bad apples"? (Quoth my thin blue line next door neighbor.) To that world view, nothing wrong is systemic; it's all down to individuals whose behavior is not considered part of the whole.
Incidentally, I'm not sure he's familiar with the second half of the idiom ("spoils the whole bunch").
