"Graffiti is a culture where if you're shit, everyone is quick to tell you. The mark of respect for a graffiti artists is how long your "piece" and tag stay up on a wall. Out of raw respect, other artists will not paint over something they think is good, and anyone who does paint over it better be prepared for a beat-down. However, if your stuff is no good, or if you are seen as amateur, you'll quickly find the word "lame" written all over your work. The offending person would then leave their own tag on the side as a direct challenge. The only way to get even was to be good. In the days before the mainstreaming of hip-hop culture and the appreciation of artists like Banksy, this was classic counterculture stuff."