We depend on product and service reviews to make responsible shopping decisions. But, according to a Cornell University study, consumers are horrible at discerning the difference between actual customer endorsements and fake reviews. And when pitted against Cornell’s computer program, that can detect fake hotel reviews with 90 percent accuracy, human research subjects could only spot the fake reviews 50 percent of the time.

Ugh. Really?

With 50 percent accuracy, why even bother reading reviews when we could just flip a coin and save ourselves a lot of time?

Luckily, we can train ourselves to be better at spotting fake reviews by using the same clues the Cornell software uses to sniff out online deceit. Here are some ways to spot spammy reviews.

1. The reviewer has a tiny internet presence

When it comes to researching a product, it’s important to review the reviewer. If you are shopping on Amazon, search for customer reviews marked “Amazon Verified Purchase.” Verified buyers are more likely to leave truthful comments. If you are shopping on eBay or Etsy, look at the feedback percentage. If you are using Yelp, is the reviewer a member of the Elite Squad that has been vetted by Yelp’s community managers? Are you using a site like Hotels.com that only allow reviews from customers who have actually booked rooms?

Since there’s a first time for everything, even writing reviews, if you want to check on a newbie reviewer’s credibility, just do some Google searches to put a face to the review. Many review sites require commenters to sign in through their Facebook or other social network accounts, so you can click on their profile to see that they’re a real person.

2. The review lacks detail

The Cornell study used online reviews for Chicago hotels to train their computer program to spot deceptive language. One of the extremely subtle tells of a fake hotel review is that the reviewer spends more time describing his vacation than the details of the hotel room. (Because how can you describe the mattress or the water pressure in the shower if you’ve never been there?)

Are you shopping for vacation accommodation right now? Use Cornell’s Review Skeptic to test the veracity of the hotel reviews.

3. The reviews vary wildly between websites

Get a second opinion on big-ticket items. If the majority of the reviews are glowing on one website, but a mixed bag on another, assume you are getting astroturfed and do more research before making your purchase.

4. The positive reviews were posted over a short timeframe

Does a new product have numerous five-star reviews that are time stamped to the same day or even the same hour? If so, beware. It’s likely that someone has been hired to write fake reviews to artificially boost that product’s reputation.

The exception to this rule books. Writers and publishers will send out Advance Reader Copies (ARCs) of books just prior to their release date to professional book reviewers, librarians, book scouts, and popular book bloggers. While publishers and authors have been known to game the system, professional bookworms who regularly read Advance Reader Copies and manuscripts for work only receive a free book as compensation in exchange for their review, so there’s not much of an incentive to keep them from being brutally honest.

5. The review includes staged photographs

Are there a lot of similar-looking photographs included with the reviews? The editors of Wirecutter.com used fakespot.com — a lie detector for reviews — to test the authenticity of Amazon reviews for a new brand of the earbud. The Wirecutter team became suspicious when they noticed that many of the earbud reviews contained suspiciously similar photographs.