I can't say I have done a formal study, it is just an observation in a single city. The Mint Blog published some numbers on illegal immigrants where it was claimed that over 60% of section 8 was claimed by them. Most of them get paid in cash so it is easy to adjust whatever they make to meet the section 8 qualifications. Also a lot of the households have more than one adult working so going over the $30k qualification threshold doesn't take that good of job if it is split between 2 or 3 people.

There are definitely people that have fallen on hard times and people on disability that needs the help section 8 provides, it just makes me angry that they are in the minority of people being helped.