People respond to incentives. This is why capitalism succeeded and communism failed. It's what built America.
85% of people, whether law enforcement or not, are mostly good. Not perfect, but decent individuals. The remainder is split between angels and demons. Some folks are damn near saints, and some are damn near monsters. Those folks don't entirely react very well to incentives, but they get handled (hopefully) through natural selection anyways. I don't buy the "da cops are teh evil" or "the cops completely violate the laws of probability in regards to human nature and have an absolutely squeaky clean civil rights record". It is not either extreme. But I would argue that they are being given too many negative incentives that should not be allowed to be applicable.
If you want the 85% that represents decent law enforcement officers, who are not angels nor demons, to follow the moral, legal and ethical road, just remove negative incentives. The situation will quickly become quite manageable. You'd see an end to a large number of highly unamerican but legal activity if all revenue from all tickets, fines and confiscated goods went to anything not related to law enforcement. Just assign those funds to some political sacred cow so it can never be touched. Law enforcement should NEVER be placed in the morally and ethically precarious position that their behavior defines their funding. Only a saint, which admittedly do exist, would pass up a chance to legally take from others when it could mean the difference between his own paycheck (or a close friend's) or the unemployment line. Too many departments are forced into this position. That's not fair to anyone involved. It is not fair to the officers, it is not fair to the non law enforcement community and it is not fair to our legal system.
I honestly don't think this would be too hard of a pitch to make to Congresscritters. "New revenue streams for your sacred pork!"
However, in the mean time, it would behoove a person to take responsible steps to prevent asset seizure. No good comes from tempting those that can legally steal from you. Always be careful with valuable property and be aware that you are not just trying to keep it out of the hands of criminals. Horseradish brings up a good point. Don't rely entirely on traditional physical security. Having a $300 state of the art unpickable Abloy lock protecting your guns, cash or oil paintings doesn't help you much when you are compelled to hand over your keys. Think "rubber hose cryptography techniques". While even more difficult than traditional physical security means, it is entirely possible to initiate some safeguards against coercion, even of the quasi-legal kind. Even the police cannot confiscate what they do not know exists.