I have a site analyzed by Quttera and they will tell me that there is a malware problem with the page. See here under “Scanned file analysis” and click on “Potentially Suspicious files”: http://quttera.com/detailed_report/seehotel.de
It’s not my site, it’s a customer site, but I am sure, he didn’t use iframes. And quttera is complaining some redirects to a fallback page for the Internet Explorer.
I do not believe the analysis of Quttera. But the problem is, that these services like Quttera are the basis for some virus scanners. And especially Avast will show a message that the site is malware infected. But it definitely isn’t.