A Snarkling with some experience writes in the comments section:
I've found it very interesting over the past decades that I've been pursuing publication for my work that the scam agencies almost always offer a written contract and that many of the legitimate agencies do not. I gave it some thought after encountering how some of those scams used that in their dealings with writers.
Essentially, it has several purposes. One is to assure the writer that the scam agency isn't a scam. A second is to furnish the scammer with a tool that can be used to threaten the writer should the writer get wind of what's going on and attempt to refuse payment. That's why a lot of scams that do submit to publishers send the work to publishers that are a) not appropriate for the kind of manuscript content, b) sure to pass on a query so the scammer doesn't have to actually send in a full copy, or c) inappropriate and accepts queries so that there's no chance of a slip-up.
Then the scammer can produce some rejections, keep the money, and drag the writer along for as much money as can be coughed up. This way, the scammer can contest any court challenge with proof that he tried to sell the manuscript and that there was no lack of performance on his part according to the contract which the court would then have no recourse but to enforce. Unwritten contracts, scammers have learned, are harder to enforce when it comes to up front fees.
This never occurred to me.
Yet another reason to remember the First Rule of the Snark: Don't Pay An Agent before s/he sells your work. Ever. No exceptions. Never.
Thanks for a the bucket of cold water on my head.