Congratulations! Through an unexpected email or phone call, you learn you've been selected for listing in a "Who's Who"-type directory. Now, after patting yourself on the back, be prepared to reach for your wallet.

A keepsake copy of one such publication will cost you up to $900. The companies say they make selections based on "humanitarian contribution" or "leadership and professional achievement," yet there's no mention of Bill Gates, Warren Buffett or other well-known philanthropists on the pages … just people who've made their living selling insurance, operating beauty salons or manufacturing ladies' clothing. The 2012 "Executives of the Year" for one registry are a retired business professor from a small Montana college and the director of a nonprofit in Chicago that helps immigrants from Asia and Eastern Europe.

The words "Who's Who" are in the public domain — any publisher can use them. There are old and reputable directories of that name that charge nothing and are truly discriminating in their selections. Some are published by professional organizations to cite notables in a specific occupation, say surgery or engineering.

But there's a whole group of less trustworthy ones that try to profit from the cachet the legit ones carry.

It's not that people listed in the vanity directories are necessarily undeserving of recognition; many are hard-working professionals making valuable contributions to society. It's just that the qualifying criteria may be less "outstanding" than what's suggested in the titles.

"In most cases," notes the Better Business Bureau, "the [publisher] doesn't turn down any nominee or entry." In fact, honorees are often recruited via mass-sent "congratulations" emails or phone calls in hopes that ego-stroking or hard-sell tactics will elicit the spending of big bucks on "memberships," commemorative plaques and/or souvenir copies.

Many directories are touted for their usefulness in "networking," but they typically aren't available in libraries or bookstores, only online. — Peter Dazeley/Getty Images

The latest sales method, report some candidates: Telemarketers falsely claiming they are calling from Google Books. More accurately, a three-year-old registry is posted on Google Books, along with countless other publications.

Here's what else you should know if told you've been selected for one of these registries.

• Your credit card may be immediately charged — "before I even received forms" to submit a biography, writes one recent selectee. "They assured me it would cost nothing; the next month there was a $700-plus charge on my credit card."

Next: How to tell whether it's a reputable publication? »