Try buying a bottle of Matrix Biolage Hydrasource shampoo on Amazon and you may very well be directed to the listing of a Prime seller with a 99 percent rating from buyers. What you won't see is that in early February, a customer left a one-star review of that seller and wrote that "the cap on the shampoo was broken and shampoo had spilled," leaving the bottle half empty. In January, another reviewer wrote a two-star rating, claiming that the "product had leaked all over the packaging." Buyers of lipstick, baby formula and pet supplies all face the same problem on Amazon. While the site makes it incredibly easy to purchase virtually anything under the sun, generally at the cheapest available price, getting an accurate and complete picture of the seller is almost impossible. It's an issue that's gaining importance, now that over half the items sold on Amazon come from third-party sellers, and that includes sensitive items like food and skincare products. Rob Dunkel, the founder of a small 12-person software company in Chicago, has taken it upon himself to help consumers get the seller details they most need before making buying decisions. His start-up — 3PM Solutions — has just released a free tool called ReconBob that any consumer can download as a plug-in for Google's Chrome browser.

Rob Dunkel, president and founder of 3PM Solutions Darren Weaver | CNBC

ReconBob is designed to bring relevant reviews to the surface that may otherwise be buried, and to direct shoppers to the most trustworthy sellers. It assumes that the buyer will want to know if merchants are selling expired goods, selling used products as new, hawking knockoffs, or if their items come with broken seals -- even if these things happen only occasionally. "It helps them understand who they're buying from on Amazon and creates transparency," Dunkel told CNBC. "We want consumers to look and learn a little more about who the seller is." Dunkel is introducing ReconBob at a time when Amazon's marketplace is coming under greater scrutiny. In a recent report, the Government Accountability Office said that 20 of the 47 products purchased by investigators from third-party sellers on major e-commerce sites including Amazon were counterfeits. And last week, the maker of an under-desk headphone mount called the Anchor wrote a blog post titled "Amazon is complicit with counterfeiting," and said that scammers were flooding the site with fakes. "Customers are unknowingly buying crap versions of the product, while both Amazon and the scammers are profiting, and the reputation you've built goes down the toilet," Elevation Lab wrote in the post, which has since gone viral. Amazon has been taking to steps to crack down on counterfeiters, filing lawsuits on Thursday against sellers of fake Vera Bradley handbags and Otterbox phone cases. But Amazon won't be able to litigate its way out of this massive and growing problem. "We strictly prohibit the sale of counterfeit products and invest heavily – both funds and company energy – to ensure our policy against the sale of such products is followed," an Amazon spokesperson said in a statement. "We remove suspected counterfeit items as soon as we become aware of them, and we remove bad actors from selling on Amazon. We have successfully taken legal action against a number of bad actors and will continue to pursue legal action and work with law enforcement." The company also said that it employs teams of engineers, research scientists and investigators for its anti-counterfeiting program and invests in "innovative machine learning and automated systems to anticipate and stay ahead of bad actors."

'Be Cautious'

Other tools exist to help consumers shop smarter online. A browser extension called Fakespot, for example, provides consumers with an assessment of product reviews and gives an A to F rating based on the trustworthiness of the comments. But ReconBob is focused on the seller of the product rather than the product itself. A shopper with the ReconBob plug-in would see every seller labeled as "Approved" in green or "Be Cautious" in amber. Clicking on the seller's storefront name would then pull up a screen that has the reviews Amazon shows on the top of the page, followed by the reviews that 3PM's predictive software determines to be most important to the shopper on the bottom. In some cases, ReconBob will pop up with a purple notice that says "Bob's Choice." By clicking "Go," the shopper will be redirected to an approved seller of that product. In Matrix's case, that means getting sent to the manufacturer's own listing.

According to Dunkel, there's a fundamental flaw in how Amazon displays buyer comments. The site allows users to sort by star rating for product reviews but not seller reviews, so there's no way to specifically look at negative shopping experiences. Buyers reading seller reviews from newest to oldest can only click "next" so many times before Amazon stops surfacing information. For the seller of Matrix Biolage shampoo, no reviews are visible before Feb. 12, 2018. The seller is also protected from certain types of negative reviews because it uses Fulfillment by Amazon (FBA), a service that allows merchants to store their goods in Amazon's warehouses and plug into its logistics and shipping systems for all transactions. When a buyer leaves a bad review of an FBA seller and the complaint can possibly be attributed to a shipping or delivery issues, Amazon says — "Message from Amazon: This item was fulfilled by Amazon, and we take responsibility for this fulfillment experience." In those instances, the star rating isn't counted against the seller.