They *can* leave marks on other stuff - which is why they say to not let your kids color on furniture etc. They are for people who are too anal about letting their kids have regular markers/paints and don't want to clean up a mess if the kids get stuff elsewhere. I personally love the markers for when we're out & about - in the car, in waiting rooms, etc. And I've never has spots left on anything from the stuff, though I've seen a couple questions here about how to remove marks from furniture/carpet.
at 3:55 PM on Oct. 2, 2010
i got this for my kids and love it...they only color on the color wonder paper and it was the best idea EVER made...
yep, they only work on the proper paper. my boys loved them. i think i introduced around 2ish maybe? the hidden pictures are fun, other wise we just use regular makers. wondercolor paper and coloring books are on the pricey side.