Would you like your home to be ravaged by the random graffiti that you did not ask for?
There was a question posed the other day "What car could you possibly be driving that would mean 10% of your driving tickets is a number greater than 1?" Instead of saying the figure may have been an exaggeration the answer was basically, "I drive a racecar."
If it is a monocolored tag made by random kid? I wouldn't.
If it was something that took skill to do, even a tag? why not, if i found that person i would pay them to make something awesome on my wall.