I don't think I would even try the "solo spray" plastic, but I bought a used German Muesing last year that was a red plastic coated alum frame. It wasn't shiny, but it did look good and was actually very durable. HOWEVER--
i WOUND UP STRIPPING IT FOR PARTS (NICE OLDER 105) because the plastic coating hid a vertical split in the back of the steering tube. It was about 2 mm wide and 20 mm long. The plastic coating was thick and flexible enough that the break was invisible from the outside.