I really don't like to permanently paint or alter any of my equipment.
I, too, thought of public confusion regarding my Pentax Spot, so I wrapped a piece of yellow electrician's [type] tape around the lens barrel.
This type of tape is available in many colors, I just happened to have some yellow on hand. No problems, no worries.
If necessary in the future, with a bit of solvent, any tape residue will be easily removed.