One who sees a fellow officer speeding and looks the other way is is of weak conscience and is undeserving to have such authority.
If that's the standard then they're all corrupt because I've never seen a cop that didn't speed with impunity, none of them pay any attention to speed limits.
The navy base in the town 40 miles from my house has a counter drug academy that trains regional police in drug tactics. The school lets out on a Friday afternoon so the cops are driving home then. Not long ago on the interstate near my house I was passed by a Louisiana cop car headed south doing well over 100 mph, I'm pretty sure he was going home from the counter drug academy training. He certainly wasn't in pursuit of someone because he wasn't even in his own state, but he felt he could drive 100 mph plus on a Mississippi interstate because he knew he'd never be cited for it, professional courtesy.
Is that corruption? I think it is but I'd guess most police officers wouldn't consider it such because they virtually all do it and are never held accountable. It's just become accepted as a perk of the job to be able to ignore traffic laws.
