Most automotive primers and paints are super thin these days even when applied in several coats so IMO painting doesn't really affect the horns in any way other than to add color.
The naked horns have a decent surface that is relatively smooth with only a few small pin head bumps but the mold markings are somewhat noticeable from a distance of 3-4 feet. The plastic horns, painted or painted, can be maintained with a window cleaner like Windex.
La Scalas are good!
Ron
