A new study by cybersecurity researchers has found that 24 percent of Facebook ads selling luxury goods, like Ray Ban sunglasses or Louis Vuitton handbags, are hocking counterfeit products.

To conduct their study, the researchers set up 12 fake Facebook accounts and looked at a sample of 180 Facebook ads for luxury goods. 43 of the ads went to websites that sold counterfeit goods. Many of the domains were registered in China and used Chinese-affiliated email accounts, though the websites themselves looked legit. Many featured realistic-seeming URLs and logos of security companies.

“You don’t know where you’re going to end up,” researcher Andrea Stroppa told Mashable. “And in many cases your credit card is at risk, thanks to obscure payment systems backed by companies you have no idea who they are.”

Facebook doesn’t disclose how many fake ads it removes from its pages, though it’s likely in the tens, if not hundreds, of millions; in 2013 alone, Google removed more than 350 million bad ads.

The easies way to avoid falling prey to these scams is simple: view Facebook ads with a critical eye. If it seems too good to be true (Louis Vuitton handbags for a quarter of their regular price?), it probably is.