https://marco.org/2007/10/23/an-affiliate-marketing-spammers-site-was
An affiliate-marketing spammer’s site was dedicated to a “professional” dog-breed selection book. You pay them $30 and they tell you that certain dogs are huge or rowdy: information you can find for free from many other sites.
Affiliate links to ebooks like this are the only significant spam source on Tumblr.
I feel guilty sometimes by suspending them - not because I think it’s unfair (I don’t), but because some sleazy internet used car salesman has convinced so many desperate, hopeful people that they can make a legitimate living this way.