No Marker Zone

I wish I could find one of those signs with a picture of a "no no" item in a circle with a slash accross the middle for markers. I would definitely start posting them around the house.
After what seemed like countless hours scrubbing the upstairs walls ( which, I am not sure did much good, what they really need is a new coat of paint), I've decided to make our house a NO MARKER ZONE.
Of course, I can't entirely blame the under 5 crowd. In my exuberance to snag "back to school" deals I inadvertently bought the non-washable type markers this year.
Still, there must be a little gnome around here who is quite fond of drawing on walls. I'm not sure who the main perpetrator is but I found the letters " J. E. D" quite a bit mixed in with other detailed scribbles.

An added thought on this. Dirty upstairs walls are one of those things that always escape my notice until I have someone over. It took walking down the hall with Nita on New Year's Day for me to say to myself "Gosh, these walls are FILTHY!". There are so many things like that these days. Case in point....I also realized that the attempt I made about 3 years ago to patch some cracks in the plaster upstairs are still in the spackled, bumpy, unsanded point. Really.....