I saw on a different forum that there was a way to get rid of this, I tried it once and it worked but I cannot remember it now, it consisted of making a back up of the save and moving some of the old files back, I just don't remember what ones,
I know that it only affects the loading screen but I dunno, I think it makes me guilty
It probably has something to do with changing one of the tags in the save files. I'd assume once a cheat has been used, a flag goes up, and the grafitti appears. It's a matter of removing said flag. I'll take a look. Maybe come up with something.