From what little research I've done, it seems to depend on the type of pen/marker used and the type of paper that's been signed.
I purchased a bus shelter recently with a huge ugly signature that I'm going to try and remove. It's signed in marker and the bus shelter is the thicker vinyl type of material. I don't have high hopes but I paid a fraction of what I've seen them go for in the past so worth a try.
If I have success I'll report back.