I had to have the tenants evicted from my old home & they finally got moved out this week. What they left was a disaster. Every wall had been literally COVERED with crayon. Normally I would use a Shieldz Primer and 2 coat it but I've seen some ads on TV about interior paints made by Olympic & others that will cover anything. I guess I'm about to find out if they are correct. I'll keep you posted. Meanwhile, has anyone else here had a similar experience? What did you use?