1) There are always drugs when property is seized this way. I review every single civil forfeiture in a rather large county, and the affidavits officers submit read something like: "I stopped Bob after an informant purchased a large amount of heroin from Bob, Bob had syringes, heroin, weed, a scale for weighing drugs etc... on his person, and a rolled up wade of bills". The money is then seized as proceeds of prohibited conduct.
2) IT IS NOT DIFFICULT TO CONTEST A CIVIL FORFEITURE. The defendant is given a single piece of paper, that is insanely easy to understand, and simply has to sign the paper saying the forfeited property is not proceeds of a crime. They then have to appear in court, before a judge, and demonstrate this fact. The bar is not high, but I have never once seen this happen.
3) The money does not all go directly to the seizing agency. Much of it goes towards drugs programs, oversight for civil forfeitures, and other programs. See, for example: http://www.oregonlaws.org/ors/131A.360
Perhaps at the federal level things work very differently and the process is abused, but every time I see these articles it really feels like an anomaly of a story is used to paint an entire program as being demonic, with little to no data to back up the conclusion.
edited for clarity, the statutory language is "prohibited conduct" not "criminal activity"