Customers leave a struggling waitress a $12,000 tip. Thinking they may have accidentally left it behind, the waitress calls the police. When the deadline for someone to claim the money passes, the police then tell the waitress that, well, they’re going to keep the money, because it’s probably drug money. They do generously offer to giver her $1,000 for letting them seize her cash.
Of course, even if it was drug money, the waitress had nothing to do with the drug crimes behind the money. And once the cash was given to her, I think most reasonable people would agree she should be allowed to keep it (the exception would of course be if it had been stolen).
But the legal fiction underlying civil asset forfeiture is that the property is guilty of the crime. So if the money was used in a drug transaction (and some jurisdictions now even argue if the money will be used in a transaction at some point in the future), the money itself is at fault, and must be forfeited, no matter who happens to be in possession of it.
Once the cash is deemed guilty, the government gets to keep it. And spend it on government things.
I guess at that point the cash is no longer guilty. It’s just dirty.