Ever since some of the original Animal Crossing games, players have had the option to purchase art for their museum from Crazy Redd.
"Jolly Redd's Treasure Trawler" docks on the shore of the secret beach, or is takes a place on Harv's Island, as of the 2.0 update.
When buying art from Redd, he will only sell one real painting or sculpture at a time.
Here's how to tell the fake Detailed Painting, based on Itō Jakuchū's Rooster and Hen with Hydrangeas, from the real one.
ACNH Detailed Painting Real vs. Fake: How to Tell
The reason players specifically need to look for real art is because the museum will absolutely not take fake art.
Not only can forged art not be donated to the Museum, but it also can't be sold to Timmy and Tommy at Nook’s Cranny. This means that the player will waste money, as the only things that can be down with forged art is that it can be disposed, displayed anywhere on the island, or within players' homes.
So, here's how to tell the real version of the Detailed Painting from the fake version.
The real Detailed Painting will have blue flowers, while the fake will have red flowers. The two versions of the painting are pictured above.