The trick is when you go out for a day to keep your wallet empty of cash, simply have your cards in there but no money.
I've travelled just about anywhere like this and the 'sorry man, no cash' works fine every time (I have some in my back pocket but I'm not going to tell a guy like this about that).
I also instantly lose any ability to speak a word of the local language and my English, so they're going to have to explain everything to me in Dutch (fat chance of getting more than 2 words across, within minutes they'll be reduced to sign language and scribbling pictures on pieces of paper). This takes a long long time. It usually does not take more than 5 minutes of this before they'll move on to the next target, their time is valuable.
When they get off shift they will have to pay their boss his part of the take, if you are hurting their figures by taking more time than average and it looks like you won't be paying or can't pay they'll shift their attention to someone more profitable.
To date this trick has been used and verified to work in: Romania, Poland, Italy, Colombia & Panama. What those countries have in common is a police force that earns relatively little money and very little oversight.
Small time corruption eradication starts with you, the tourist. If you're going to be a fat sitting duck and you pay up too easily when you've done nothing wrong then you carry a part responsibility for keeping things that way.
The Romanian police was actually really funny, they started off with 1500 Euros in fines (my crime actually was better described as 'driving with a foreign license plate'), quickly dropped to about 100 Euros and then when they found out that I didn't have any money centered on impounding the car. When I readily agreed to that they sent me on my way...
I positively hate corrupt police. Don't pay them.
