Websites offering unbelievable deals could be too good to be true this holiday season.

Mashable.com editor-in-chief Lance Ulanoff says a lot of questionable websites pop up around this time of year. They could be selling knock-off merchandise or could just want to steal customers' money or personal information.

Telltale signs of fraud are shoddy website design, poor spelling and foreign company addresses, Ulanoff says.

Ulanoff says consumers should read online comments and reviews. He says customers should not enter credit card information until they have made sure the site is secure with an HTTPS web address.