When "Newlyweds: Nick & Jessica" ran on MTV from 2003 to 2005, viewers learned that Lachey was frugal (he famously refused to hire movers to help him clear out his bachelor pad) and Simpson didn't know whether Chicken of the Sea was really fish or chicken (for the record, it's tuna.)
One of the producers behind the series now says despite reality TV's reputation for scripting, they showed the real Lachey and Simpson.
"They were nice," Sue Kolinsky told Complex magazine.
"Nick was a little more accessible than Jessica, but she was very sweet and it was fun hanging out with them."
Kolinsky served as a producer through the duration of the series after working on "The Osbournes," which featured rocker Ozzy and his family.
She said she had a choice between working on "Rich Girls," which followed the adventures of Tommy Hilfiger's daughter and her friends or "Newlyweds."
"I just chose 'Newlyweds' because it sounded fun to be inside the world of somebody's brand new marriage," she said. "As soon as we started looking at the footage and I saw the 'Is this chicken or fish?' [scene], I knew it was going to be a really fun ride."
Kolinsky said the couple was perfect for reality TV "because they were polar opposites, they were beautiful, and without even realizing it, they were very funny."
A lot of the humor came via Simpson's scatterbrained moments, which the producer said were genuine.
"There were times when we were like, 'Hm, does she really not know what this means?,'" Kolinsky said. "I remember there was a scene where there was a dead mouse by their pool and it had been dead for a while. Nick said, 'It's in rigor mortis' and Jessica said, 'Riga-what?'"
The honeymoon didn't last, however, and the couple split soon after the show ended.
Kolinsky said tension developed on the set as Lachey and Simpson found it difficult to overcome their differences.
"In the end they weren't suited for each other. The only thing they really had in common was their music, " Kolinsky said.
Their divorce was finalized in 2006.
Lachey married former MTV personality Vanessa Lachey in 2011. They are now the parents of two sons and a daughter.
Simpson married former NFL football player Eric Johnson in 2014. The couple has a son and a daughter.
But Simpson has never been able to escape that whole Chicken of the Sea incident.
This week, she poked fun at it on Twitter, posting a photo of a headline about supermarket chain Whole Foods discovering there was tuna in their chicken salad.
"It happens to the best of us @WholeFoods," Simpson tweeted.