The more outrageous and obvious Nigerian scammersâ€™ offers of untold West African riches are, the more likely they are to turn out profitable for the scammers, shows the latest Microsoft research.

The study shows Nigerian scammers, far from being too dim to come up with something more creative, are carefully crafted to sift out scam-savvy targets and leave them with only the most gullible. By announcing they are Nigerian and that they need your help to transfer millions of dollars or some such scam, the cyber crooks increase their efficiency, allowing them to spend their time only on the easiest of targets.

â€œThose who remain are the scammersâ€™ ideal targets,â€ said Microsoft researcher Cormac Herley in a paper titled Why Do Nigerian Scammers Say They are from Nigeria? â€œA less outlandish wording that did not mention Nigeria would almost certainly gather more total responses and more viable responses, but would yield lower overall proï¬t.â€

The paper focuses on false positives that make many promising detection technologies unworkable in practice. Cyber attackers have the same problem too in deciding whom to target. True positives are targets successfully attacked, while false positives are those attacked that yield nothing.

Though the far-fetched tales of West African riches strike most as comical, the analysis suggests that is an advantage to the attacker. Nigerian scammers end up with a list of self-selected hot targets, less work than would be required with more plausible tales, and bigger amounts of money earned.

â€œAn email with tales of fabulous amounts of money and West African corruption will strike all but the most gullible as bizarre,â€ Herley said. â€œIt will be recognized and ignored by anyone who has been using the Internet long enough to have seen it several times. It will be ï¬gured out by anyone savvy enough to use a search engine [and] wonâ€™t be pursued by anyone who consults sensible family or friends, or who reads any of the advice banks and money transfer agencies make available.â€

People who still fall for Nigerian scams represent a tiny subset of the overall population. Only one in 10,000 or fewer are still tricked by these money schemes.