At the beginning of September, Alejandro Bedoya, a professional soccer player and the captain of the Philadelphia Union, tweeted a picture of three cartons of Organic Valley reduced fat milk. "I’ve been an @amazon Prime member for a while now and just had a Fresh delivery a couple days ago but never expected to have sick kids from drinking bad milk that’s been expired for over 6 weeks," he wrote.

Sure enough, two of the cartons in the pic were stamped with a July 20 expiration date, which might explain why Bedoya had to use the vomiting emoji in his post.

According to a recent report from CNBC, he's not alone. The news outlet double-clicked its way through Amazon's Grocery & Gourmet category, and found that customers have complained about receiving a wide range of products that had already expired. There were reports of moldy beef jerky, outdated baby formula and baby food, stale Doritos, year-old Hostess brownies, and "chunky and gross" coffee creamer, among countless others.

A data analytics firm did an even deeper dive into the Amazon Marketplace––the section of the site where third-party sellers list their products for sale––and discovered that 40 percent of the sellers who offered some of Amazon's 100 best-selling food products had each received at least five complaints about expired items.

"We work hard to make sure customers receive high-quality products when they order from our store. We have robust processes in place to ensure customers receive products with sufficient shelf life," a spokesperson said. "If customers have concerns about items they’ve purchased, we encourage them to contact our Customer Service directly and work with us so we can investigate and take appropriate action."

Amazon also told CNBC that third-party sellers are all required to provide the expiration date of any product they're selling that is "meant for consumption," and they also have to ensure that those items have at least 90 days before they hit their expiration or sell-by dates. (But when CNBC brought some expiration-related complaints to Amazon's attention, the company said they were "isolated incidents" that didn't require them to take action against the sellers or remove any products from the site.)

Thomas Gremillion, director of food policy at the Consumer Federation of America, essentially said that approach is part of the problem. "There’s no indication of how well that policy is enforced,” he said. “Some sellers could be making a business decision to sell expired products and let Amazon catch some of it and toss it out and persist.”

This issue isn't unique to food products: in 2017, some Amazon customers reported receiving boxes of Opcicon One Step, a generic version of emergency contraception, that were some six months past their sell-by date. Some of the third-party vendors who were selling the medication had placed stickers over the expiration dates or had scratched them off the boxes. (Although Amazon removed one vendor from its Marketplace, other sellers were still listing the product for sale, and, without ordering it, there was no way of knowing whether it was also out of date.)