Popcorn acoustic ceilings
The shag carpet from the '60s or '70s was replaced long ago. But acoustic popcorn ceilings, another artifact of that era (and of the '80s, too) might remain. They badly date your space.
If you can't stomach the cost or the mess to remove the overhead popcorn, be prepared to credit a buyer in certain markets in order to close a sale.
"The popcorn acoustic ceiling is a major, major turnoff to buyers these days," Goldwasser says.