LG Digital Media
Try using isopropyl alcohol (rubbing alcohol) to clean the graffitti off the graphic. It will not harm the laminate and takes off most paint and ink. If it's a persistent problem then switch to the anti-graffitti laminate that offers greater chemical resistance so you can use stronger solvent cleaners.
LG digital media is a fairly new brand on the market so you don't hear a lot of talk about it. Like every other brand it has economy, intermediate, and high performance grades. Generally it is lower cost and oftentimes higher quality at the same time. Ask you dealer to help guide your decision making. We are using the LS2710 because it's cheap ($109 for a 54" x 150' roll) and phthalate-free so better for environment/personal health.
Hope this helps you!
-Bud