Exactly what the police needs. Maybe they'll stop taking friggin' rishwat from jerks. Downside is this works in a rich area, but poor areas who can't support their police in this manner will continue to have police departments that don't take their job seriously.
Not all giving rishwat are jerks, e.g. I had do give rishwat even for some legal work done I had no choice.
Al-Raashti Wal-Murshati Kala Huma Fil-Naar..
Both the giver and taker of bribes will end up in hell.