
But who wrote them? Are they good for college level?
This was asked several years ago, but I wanted to add my thought for those newer readers.
We can "assume" that mill papers are written by college students, but no one has a way of knowing for sure.
A few years ago, I conducted research on paper mills and found that many papers are cut/paste from wiki sites and some are articles or blog posts pasted into a document.
So, potential clients will want to be very careful of purchasing from a paper database. If you find that a purchased paper is in fact copy/paste, you likely have little recourse.
The companies reselling these documents are fully aware that not all papers are "real" papers. They don't care as long as the sale is made. Once they have your $, you're on your own.
Bottom line: approach any reselling service with caution. It's always best to use custom writing services or a freelance writer. If money is the issue (as I know it is for many), request a sample that you can then check for originality.
No sample? Write it yourself. Yes, that's opposite the reason you went searching for a paper in the first place, I'm sure, but it all depends on whether you want to risk using "stolen" material whether you're citing it or not. ;)