There is if it is not cleaned properly. But if you use cleaning fluid and an eraser, it is gone as if it was chalk on a blackboard.

I agree with @zenvelo. The color stays there if you only wipe it with a dry cloth or tissue or use only water. The true dry erase solvent uses alcohol as the main ingredient. (Some use vinegar). That dissolves the ink and smears it when a paper towel or eraser goes over it.

Also a new dry erase marker will dissolve the writing underneath it. Try the experiment. Draw some vertical lines . and let them sit for a day. Then draw some horizontal lines with a new marker and lightly erase them. You will see clean white spots at the intersection of both lines.

That said, if they are willing to spend a lot of money and time forensic scientists can read anything. See Archimedes Palipsest. A lead researcher on this project spoke at one of our meetings and explained how they did it. Incredible!

Some advanced high-tech whiteboards that can be used for teleconferencing have internal memory, just like copy and fax machines. So, their memories could be accessed, even if the surface has been “erased”.