Most sites have a disclaimer. Most assume or argue they are protected by the First Amendment. Some warn students not to turn in the papers from their sites. The School Sucks site warns students that plagiarizing the site's papers is foolish because they're so well known that teachers, professors, and the media visit the site regularly. It also quotes and acknowledges the plagiarism section in Diana Hacker's A Writer's Reference .
Sites vary greatly offering from a handful of papers to thousands.
All subject areas are available. However, the quality varies greatly from atrocious to excellent. Very few are excellent. Most offered some papers with in-text citations or footnotes and bibliographies, no extra charge. As a bonus, the site has a link that describes different ways to cheat at school on exams.