Graffiti lowers your Righteousness rating. You can see your various ratings via the Conform-O-meter (https://simpsonstappedout.fandom.com/wiki/Conform-O-Meter). The cheapest way to raise your Righteousness rating is by placing Training Walls. They are $270 IGC (In Game Currency) and found under the Decorations tab. They can easily be placed and hidden behind buildings.
Replies
https://tstoaddicts.com/2014/12/02/tappers-101-vandalism-tagging-spray-paint/