Spray paint can be found in the following colors.
-Glow in the Dark
Since they do no damage and add little in the way of stat boosts, Spray Paint is best used to mark areas players have already explored. Doorways can be designated as already scouted and pathways up and down levels can be marked as well. The spray paint can affect monsters and players.
One good strategy is to mark the straightest way to get back up. This helps the end game's ascending.
If you are painted (in coop) you can clean yourself with water.