(MONEY Magazine) – Since concerns about security, privacy or scams linger around Internet shopping, it's no surprise that an industry has popped up that aims to assuage those fears with a seal of approval. But the meaning and value of these so-called trustmarks vary widely. Some, in fact, may not be real: According to Maria LaTour Kadison, online retail analyst for Forrester Research, a few dishonest businesses are just slapping a counterfeit or phony trustmark on their sites.

Your best defense? Click on the insignia, which should connect you to the watchdog's site; read the watchdog's policy and decide for yourself if its criteria satisfy yours.

We did some clicking around to check out the more prominent trustmarks, and our view is that the Better Business Bureau's is the gold standard. To qualify, a retailer must, among other things, become a bbb member, provide detailed management information and agree to binding arbitration. The bbb even sends an agent to inspect the retailer's facility.

Few others have such strict policies. Some seals, like those offered by WebWatchdog and the Netcheck Commerce Bureau, require a merchant to do little more than fill out an application, pay a fee and perhaps provide references. Still, membership means retailers are willing to let the watchdog monitor consumer complaints. Netcheck, for example, has a page of information and consumer feedback devoted to each member.

A few other valuable trustmarks are more specialized. The American Institute of Certified Public Accountants audits a retailer before granting its CPA Webtrust seal. A firm called Trust-e gives a seal of approval based on privacy policies. And the new SiteCertain seal from the American Bankers Association confirms that a bank is complying with the appropriate regulatory agency.

--SCOTT MEDINTZ