This tagged AT-AT is currently part of a Christies auction (with a guide price of $1,500-$2,000).
"Customized Hasbro Star Wars vehicle customized by professional Graffiti artists EASE and JK5 under the direction of SUCKADELIC. All tags are written in the Aurebesh language, a fictional letter system created for the in-world use for the 6 Star Wars films. The largest tag on the side of the vehicle spells the word REBEL. "
I shall have to get out my marker pens and see if I can raise the street value of my own clean version. Nope. Couldn't do it. Sacrilege.