It's normal to assume that when using a freshly washed towel, it's just that, freshly washed and clean.
But a US man got the shock of his life after his wife tried a towel hack that revealed the clean item was anything but hygienic.
Jared Guyens took to Facebook in June to share a photo of the gross discovery which has since attracted nearly 30,000 comments and 86,000 shares from people equally as stunned by the results of the 12-hour test.
Guyens, of Rockwall, Texas, posted a photo that showed a tub filled with cloudy brown liquid that the couple's freshly washed towels produced.
He said his wife watched a YouTube tutorial on "Towel Stripping" which involves using a specific combination of household cleaning chemicals to do a deep clean of towels.
"In this case she took our collection of clean towels, let me say that again, the towels were totally clean, washed and folded and in the linen closet, completely clean, completely normal," he emphasised in the caption.
"So she took those clean towels, and put them here in the tub with this mixture of Arm & Hammer baking soda, borax and Oxi Clean, and hot water and let these things soak overnight."
Guyens, who also happens to be a nerf champion and Guinness World Record holder, explained that the reason behind the dirty water was due to built-up grime.
"The story that she [wife] told me is that over the years of use, microscopic amounts of soap and detergent get locked in to the fibres of the towels," he said.
"Subsequently that stuff gets gummed up and can also trap microscopic amount of dirt and grime and bacteria, even after going through the washing machine with detergent.
"So after seeing someone else do it she decided to do the experiment on our own towels here in the tub."
Guyens said he is "literally freaking out right now" following the discovery.
"The towels at your house, no matter how clean you think they are, are probably this nasty too," he finished the post.
Facebook users have continued to bombard his post, with one woman saying: "OMG, I need to clean my towels now!"
"OMG I hope hotels use Oxi Clean and borax with baking soda after they bleach them," another added.
But not everyone agreed with the method, with one person saying the ingredients strip the colour to cause the discoloured water.
"It's a chemical that brought most of the dye out of the towels," one Facebook user wrote.
"You're absolutely correct," another agreed, adding, "I can't believe people actually get sucked in so easily. Lolol. It happens EVERY TIME with EVERY ITEM you do because you're using the same ingredients that cause this reaction."
One woman disagreed, saying she tried it on white items and got the same result.
"I've done it with pure white clothes and gotten this result," she wrote.
"I wash my husband's work clothes two times before I call them 'clean' and I did it after I went through the washing routine and it left dirt on the bottom of my tub where it settled after water was drained," another added.
Others believe you wouldn't ever have to strip your towels if you wash them at a high temperature for long enough.
"If you wash your clothing and towels properly each time, stripping is unnecessary and this won't happen. This is what happens when you always wash on 30/quick wash – minging!"