Great question — answering as the UphillTech team:
Marker ink is usually alcohol based. But I admit that I am not sure about dry erase. If you go to the store and get a can of denatured alcohol, if it is going to work the stains should come right out without hardly any scrubbing at all. Just pour it on. I don't think the alcohol will ever affect your fabric either, but don't sue me. On the other hand, you may regret throwing out any of your old stuff if it works as good as I think it might.
Full answer by Den Warren: https://lifehacks.stackexchange.com/a/19402 (CC BY-SA 4.0).
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