New York Times story about "DecorMyEyes" is about as bad as it gets. I mean, seriously, when was the last time you heard of an attempt to return merchandise resulting in a criminal warrant for stalking being issued against the proprietor of a business?
Danny Sullivan of Search Engine Land quickly pointed out how Google was addressing customer reviews in other areas of search, and suggested steps Google could take to minimize the chance of an online consumer confusing a top result in a search engine results page with the suggestion that the merchant was honest or ethical.
To Google's credit, it appears that by that time they were already on the case, attempting to develop an algorithmic solution that will detect merchants that Google believes "provide a extremely poor user experience", and... presumably prevent them from achieving top search engine rankings. But as Google notes, they won't catch everybody.
But when you're dealing with online merchants, particularly those of which you haven't previously heard, caveat emptor. Check the reviews carefully, keeping in mind that for newer vendors a series of positive reviews may be planted for the purpose of tricking would-be customers. Check the website - not just to see if it looks professional, but to see what it says about the business, its location and phone number. No business name other than the website title? No contact information other than a phone number? Watch out. If you look up the domain name for the store (e.g., through Whois.sc) do you get a real address and contact information, fake information or an anonymous registration? Real stores don't hide.
And if it’s important enough for you to have “designer” handbags, watches, eyeglasses, etc., know up front that a huge percentage of online merchandise is going to be counterfeit or, at best, gray market - it may cost more, but consider shopping through an authorized merchant.