Just an opinion but I don't think it's about the vehicle's condition, or if it's worth the price or not.
It's about an organized gang that is defrauding people by committing a federal offence, and how to avoid, and most important, how to put them away.
If they gave you a falsified title, and that said title was printed by the CA DMV, then this is very serious and goes deep into tag agencies as well (not surprising, knowing a lot of Mickey Mouse tag agencies. Miami is FULL of them).
If it was a really good photoshopped doc printed on fancy paper, they did their research and it's very worrying as well.
Carfax, shop receipts, dealer invoices, all that can be faked by a 12 YO kid with a cheap laptop and an Adobe subscription.
A PPI won't find anything wrong on the docs, since they won't check those. They won't find mileage inconsistency either. They will find a scratch, a dent, tire wear and maybe a smokey exhaust. Most PPI companies that I deal with in a weekly, and sometimes daily manner, just come with a basic code reader, a basic paint gauge, a tire gauge and a camera/phone. Their reports are vague to say the least.
To those that were bitten by this organization, I believe it's not gonna be easy getting any restitution, besides the warm feel of revenge if / when these people fall. If it becomes too common, eventually the Feds will intervene, good luck waiting.
Just my 0.2c:
To future buyers, specially those walking around with $16k cash in their pockets (nothing wrong with cash buying btw) the Proper way to conduct the transaction is meeting at a tag agency parking lot, with all necessary tools (scanner, flashlight, magnet, UV light, whatever) and after the deal is struck, going in the tag office to finalize and exchange docs for $$). A single carfax report costs something around $30-40 or so, not bad idea to get one.
If it's a fraud attempt, they won't show up.
If the seller doesn't have the time to deal with your demands, maybe walk away.
If it's too good to be true, probably it is.
Also, this Forum is a flowing wealth of info, and ppl here are willing to help if they can. I'll be happy to run VINs if I get the chance to visit here and find the need or someone asks.