The one thing you can rely on is if you get disturbed halfway through a painting and it looks a bit naff, then someone will preserve that piece, remove it and a few months later it'll be paraded round Sotheby's by people wearing white gloves.
BanksyTraditional graffiti writers have a bunch of rules they like to stick to, and good luck to them, but I didn't become a graffiti artist so I could have somebody else tell me what to do. If you're the type who gets sentimental about people scribbling over your stuff, I suggest graffiti is probably not the right hobby for you.
Banksy