However, as they were chosen based on attractiveness rather than talent, they were not very skilled painters, and therefore it is easy to identify paintings they worked on based on their lower quality.[31] Because of the general workshop practice where multiple artists work on one painting, it has become common practice to ascribe Leonardo's pupils to his less known (or lower quality) works.[31] These might be referenced to as paintings done by his pupils that Leonardo touched up as opposed to the inverse.