We’ve all received advance-fee fraud emails claiming that if we just allow the deposed King of Tannu Tuva to deposit $26,000,000 into one of our bank accounts temporarily, we’ll be able to keep 15%. At some later point we’ll be asked to lend $5,000 (the advance fee) very temporarily to allow the transaction to go forward. Ever wonder why the fraudsters don’t make these emails more believable? Why they claim to be from Nigeria when most people (correctly or incorrectly) believe that Nigeria’s the source of most scam emails? Why they don’t tell less farcical stories about why they need our help? Why they offer such absurdly large amounts of money for otherwise readily available, inexpensive banking services?

Because they only want to get responses from the very gullible. They want the somewhat gullible to weed themselves out, so the scammers don’t have to waste months in email and phone conversations with people who will, at some point, before sending any money, figure out that they are being scammed.

There are two powerful marketing principles here: First, marketing skills can be used for good or evil. (Please, use your marketing prowess only for good—to connect people with amazing books and services that offer them real value.)

Second, your marketing should not just attract people you want to engage, but also repel people you don’t want to engage.

Anyone in any business is familiar with prospects who take up ton of times but never buy, or customers who are endlessly difficult to deal with. You want your marketing to actively repel these types of people. This principle is especially important if you are marketing using a blog and social media. There are followers who comment frequently, demanding lots of answers and attention, without any intention of ever buying your books or service. There are followers who try to steer your following in directions other than what you intended, like to their competing books and services. You want your blog and social media presence to actively repel these types of followers.

The bottom line is: Good marketing attracts your best prospects and repels your worst prospects at the same time.