Business Insider obtained a PDF guide that is sold online for just £2.59.
It details how scammers operate fake dating site profiles in order to con men out of money.
It's pretty easy to tell: They send the same message over and over, often with the same link.
But there's a type of dating site scam that's far trickier to spot, and the people who operate it claim to be making thousands of dollars every month fooling vulnerable men.
If you've used a dating site or app like Ok Cupid or Tinder, you'll have noticed the hundreds of fake profiles that exist on the sites, seemingly designed to make you hand over your profile to scammers.
Dating sites are, thankfully, getting better at spotting who is using their service to send thousands of spam messages.
The guide isn't available for free, in fact, it was being sold for Bitcoins on a deep web marketplace.
Bitcoin is cryptographic currency favoured by criminals as it allows semi-anonymous online transactions.
It's not just guns and drugs that are up for sale on deep web sites.
Vendors also list guides on how to commit other illegal activities.
The documents are often sold for small amounts of money, but the price barrier, the need to pay with Bitcoin, and the fact that they're only available on the deep web prevents the guides from being circulated widely.The document, titled Adhrann's Updated Dating Scam 2014, lays out a method for creating fake dating site profiles, ensnaring men in conversation, and then pressuring them to send money.