Paper background dirt AI removal

When using paper background is normal that shoes or feet leave some dirt on the floor.

When the background color is light, like white, it becomes very time consuming to clean everything with the healing tool. Additionally, the result is usually quite unsatisfactory.
Now that AI has been introduced in C1 as well, a good way to use it would be to implement this feature. Which is probably not that easy, because the AI should be able to select only the dirt, distinguishing among the different gradient of light and shadow that are cast on the floor or at the back and replace with "clean" colour, but with the exact level of luminosity. Additionally, stains that are across lightened and shaded areas are also critical.
I attach an example in jpg. Please contact me if you want a RAW. I'm not able to upload because the file is too large.