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If you are getting a Fail in Critical factors that means the canonical tag is pointing to a different URL then the one you are trying to grade/optimize. Are you looking at the report card of the page http://www.hometheatercooling.com/Audio-Fan.html? To be more clear, the Pass in optional Factors means that yes, you use a canonical tag, the Fail in Critical factors means your canonical tag doesn't correspond to your page url.

Just because it's made for PPC doesn't mean it can't rank on it's own. If there are things you can to to the page that will not negatively affect your conversion rate then by all means fix them and index, follow the page. btw, you could probably noindex, follow instead of noindex, nofollow.