How to prevent the banknote slot of the self-service vending machine from being artificially blocked

If people’s moral consciousness is not in place, no matter how hard they take precautions, it will be useless. Just like I have seen before, a person urinates freely under the sign posted that it is strictly prohibited to urinate and defecate here. All I can say is that self-service vending machines are not suitable for use in your place, and precautions are probably useless. However, if you are not too troublesome, you can clean them once and for all.