Re: A tiny percentage of ads are viewed by real people—who ignore them anyway
"How can one be sure reviews are really reviews and not ads in disguise?"
Oh come on, that's "how to internet 101", seriously. You just disregard absolutely all positive reviews all products of interest and only look at the negative ones. If several are complaining about a similar issue, especially on different sites, it's probably real. If the complaints are about small stuff of little substance or the big complaints look like isolated outliers, it's probably an almost decent product. Not that this is foolproof, but I have never heard of a truly concerted effort / smear campaign in the real world that could have defeated it.