Ive had new props that came painted and old props that were painted (by professionals), without fail the paint would start comeing off after a few months.
Have a look at the boats on a dry stack and see if you can find any with painted props that are more than a few months old (the props that is), bet you cant find any that the paint isnt coming off.
If it irritates you then would recommend a shiny stainless prop.
If you find a solution or method that works let us all know. LOL ...