Kubrows and Kavats can try to re-open a locker that it has tried (and failed) to open before. When a Kubrow or Kavat fails, the locker goes from red (lock) to off (black) and can't be unlocked anymore.
It is not recommended to have Master Thief on your Warframe as well as this mod, as lockers that Master Thief fails to unlock cannot be tried by your Kubrow or Kavat.
Tested on a single Invasion Mission, attempting to open all lockers granted a 15,000 credit gain per Kubrow per hour. Therefore, a full squad of Kubrows with Scavenge can grant approximately 1,000 credits per minute.
Sometimes, when executing the skill your Kubrow will "scratch" on the opposite side of the locker (scratching the air). However this is only an animation bug and the targeted locker is still being unlocked normally.
If you have Master Thief and unlock the locker as the Kubrow begins to walk over to attempt to unlock it, this will actually appear to re-lock the locker, but only visually.