MIAMI -- If you like to shop on Internet marketplace sites: buyer and seller both need to beware.

A South Florida consumer advocate is cracking down on some slippery con artists, and helping consumers steer clear of a slippery scam.

"Yes, people do get ripped off on Ebay and other similar sites like Auto Trader, and Yahoo Classified.," says Jeff Ostroff. "Basically, any place where there's an on line market, they can get ripped off."

Ostroff says the scam happens through fake escrow sites -- sites where money is supposedly held safe and secure for buyers and sellers.

"Out of 400 websites that we've looked into, virtually 99 percent of them are fake escrows," says Ostroff.

The sites are easy to spot if you know what to look for:

Watch out for words like "safe" and "secure in the name of the site. "They tend to spoof branded names like Ebay, they'll call themselves 'safer bay'. We just shut one down the other day called 'Safer Bay US'," says Ostroff.

A hyphen or dash in the name is often another warning sign of a fake escrow site.

Ostroff says they also rip off logos from legitimate escrow sites. "They have fake 'Verisign' logos and when you go to register it will not be a secure site, you won't see the little lock icon at the bottom of your browser window."

To protect yourself, never log onto a site through an email; be suspicious of sites that pay shipping and escrow fees on big ticket items; never use cash transfer services; confirm the company's basic information like phone number and address.

For more information, check out consumer advocate Jeff Ostroff's Web site www.carbuyingtips.com.