And WSJ explains why the scam emails sent out sound so dumb:
So why do the scammers persist in blanketing the world with outlandish propositions, announcing that they are from the very country whose name has become synonymous with online fraud?
Cormac Herley, a computer scientist at Microsoft Research who specializes in security issues, provides a convincing answer in a paper presented at a conference in Berlin and recently published on his website. In it, he analyzes the con mathematically, using an approach called signal detection theory. His crucial insight is to look at the situation not from the victim's point of view but from that of the scammers. Their challenge is to hook only people who will get sucked in deeply enough to send a significant amount of money—the "true positives." They must minimize the effort they devote to "false positives" (targets who might seem like dupes but are suspicious and/or never pay up).
It costs the scammers virtually nothing to spam the world, but it costs them a lot (especially in terms of time) to conduct all the follow-ups necessary to reel a sucker all the way in...
A proposal offering a more realistic scenario might generate more replies, but most of them wouldn't pan out. The effort of sorting through them to find the real suckers would undermine the scheme's profitability. Instead, by screaming "This is another absurd instance of the familiar Nigerian scam," the fraudsters are filtering out what to them is spam—responses from suspicious people they don't want to deal with—and "letting through" only those most likely to play along. The fewer potential victims in the world, the more precisely the scammers must target them, and thus the more absurd and easy-to-spot the attacks should be.