I have been laser cutting wood that is pre-painted with both Valspar gold spray paint and Rustoleum gold. I got a message from Rustoleum manufacturer that it was safe, and the Valspar seems to have similar ingredients list. It works great -- no odors, no fumes trying to kill me -- BUT >> important >> you *must* let it cure the full 48 hours that it says on the can. You can't just do this quick. The metallic paints have more reaction to the laser heat... if they haven't fully cured, and you will get a lot of melting and heat scoring.
I don't know if you will have the same effect with the brush-on paints. Find a can of Rustoleum and compare ingredients, maybe?