I like your words, conspiracybeliever.
People here are talking as if it would only be the poorest of the poor who do drugs. But if you go higher up in society, you'll notice that plenty of people are on drugs on a regular basis. It is just different drugs, which are not that easy to spot, and where your physique does not change that rapidly. Especially the white powder is consumed by many in economy and politics.
If you want to drug test welfare recipients, fine, but then test everyone else who is receiving money from the state as well. The current salary (2011-2012) for rank-and-file members of the House and Senate is $174,000 per year.