From my research, I’ve learned that the per-sale model is about the only one in use. Spammers who are working as affiliates for a merchant or a king-pin spammer are almost always paid on commission. They get around 25-40% of all sales that they manage to drive to the target site. Or, in the case of something like mortgages, they get a set dollar amount ($25 is typical) per “lead” they generate.

Some spammers get paid a smaller commission for “opens” (measured by web bugs in the emails), but these spammers are rarer and tend to be “opt in” marketers sending email on behalf of large, “legitimate” companies.

Note also that many spammers are NOT spamming as a sales affiliate on behalf of a merchant. A sizable number of them — especially the ones who sell diet and penis-enlargement pills — often retail a private-label product. E.g., they buy the product for $5 per bottle in bulk from a wholesaler and turn around and sell it for $50 per bottle.

Now, you ask, why do spammers try so hard to slip past filters? Why are they marketing to people who seem not to want their messages?

Remember, spammers are sales people, just like the door-to-door encyclopedia or vacuum-cleaner salesmen of yore. It’s a profession that rewards stubbornness and persistence. (People absolutely hated telemarketing too, but it apparently was a successful sales channel.)

What’s more, my research has shown that a significant number of people actually visit sites touted in spams that have properly been filtered into a spam folder.

So, to your bottom-line question: could spam die? I say that will only happen if demand dries up and people stop buying from spammers. I believe that spammers are catering to a niche of what I call “furtive shoppers,” and it’s unlikely that niche will disappear completely anytime soon.