Here is a very sad case of someone who really needed it and was denied:
Perry: I don't have problem with drug-testing welfare recipients
Texas Gov. Rick Perry said Wednesday he wouldn't be opposed to welfare recipients also being drug tested, joining fellow candidate Newt Gingrich in suggesting that federal aid should be tied to substance use. Ref. Source 9
Http://www.msnbc.msn.com/id/25727901/ns/us_news-life/t/illegal-immigrants-spurn-needed-benefits/
Most food gets checked out through some kind of computer scanner now so you'd think they would have some kind of process to tell patrons they cannot buy 'that' particular item using food stamps.