Razib: i have to disagree with megan re: the stupidity of poor people. THEY ARE usually stupid.
There are studies showing that many inner city residents do not have ready access to produce and other healthy food since those type of businesses shy away from setting up shop in those neighborhoods -- sometimes its even hard to frequent a full grocery store or supermarket. Not true for fast food establishments though which are generally plentiful. I believe that it was Newark NJ that set up a program to offer better access to fruits and vegetables with good results. Community gardens in the inner city have also proven useful in getting those residents to eat better.
As Ta-Nehisi said, your environment and companions can really affect your perceptions of what is acceptable and/or attractive. So while poor people are often uneducated, it's certainly not hopeless.