Good question with a pretty ambiguous answer for anyone that’d try to answer.
For me it’s a combination of skill, intention, and impact. Like a shaky handed sharpie tag on a bus stop isn’t much of anything, but when it says, “kill your local heroin dealer” that’s impactful. The shaky lines start to show the styling they had intended but can’t capture anymore. I’d call that art even though it was painted over a week later.