I personally think that graffiti, and vandalism in general, is a very cool form of self expression. I'm talking tagging, full pieces, street art, stickers and posters on traffic poles, removing anti-homeless infrastructure, etc, etc. All fucking wonderful means of art. Personally I think that there are some moral limits to what is okay and what isn't to vandalise e.g. (example) but other than a few edge cases literally anything is fair game. Risking arrest and punishment just to put your work out there is something very special. I have mad respect for anyone that does it.
I want to display the kinds of graffiti you can find in my area (undisclosed for obvious reasons). I've included hover text with some basic info on the graffiti and what the tags say (i'm not an expert, there will be mistakes).