"We think this information must be clearly disclosed to consumers," said Ruth Susswein with the advocacy group Consumer Action. "Sometimes it is and sometimes it isn't."
Based on its survey, Consumer Action says you'd be smart to visit several sites before applying for a card. And check the articles posted on these sites.
"Because tucked away in the articles are some of the best offers; sometimes even better than on the comparison section of the site," Susswein said.
Remember: some cards are not listed on these sites, such as those from local banks and credit unions. Chances are you won't find anything from Bank of America, because B of A generally does not pay referral fees to these websites.
More: Credit Card Comparison Sites Might Be Biased
Read: Consumer Action Survey