LAS VEGAS (KLAS) — Many look to reviews to determine whether or not a product is worth purchasing online but how can a shopper tell whether reviews are legitimate, and which products are more likely to have fake reviews?

Saoud Khalifah, founder of Fakespot, an extension that detects fake reviews and scams, said his business started with precisely those questions. Khalifah said he was ordering well-reviewed supplements online, and receiving pills filled with sawdust.

 “I went and took a closer look at those reviews and realized they were either people that were compensated by the seller to write those five-star reviews, or they were bots,” said Khalifah.

He said he created Fakespot to help consumers spot fraudulent reviews as they shop online.

“It will automate the analysis, look at the reviews, look at the profile, and the seller to find patterns of deception — something that is not natural,” said Khalifah.

Product categories with a C grade or worse are the most riddled with fake reviews, Khalifah said. Those categories include earbuds, chargers, sneakers, smartwatches, smartphones, and backpacks.

Khalifah notes some red flags to keep an eye out for, including reviews that use similar language or speak to the quality of the company but not the product. Additionally, he notes that review typos and products with bursts of five-star reviews posted within a short period of time could signal that something is off.

The lowest number of fake reviews, Khalifah says, are present in listings for monitors, phone cases, batteries, and water bottles.