In this task you will learn how to remove stains or replace any part of an object in your picture that you don't like, and make it look cleaner, or smoother. This is a complex task. To get good results, lots of practice is needed, so don't get frustrated if on the first try you don't get the results you want!
Load the picture with the object you want to clean. I'll be using the following image:
I really like this picture from a fountain in Rome, what I don't like is the rusty stain on the faun's chin (I think it's a faun). To clean this image, I carried out the following procedure:
Select the Clone Tool, and pick a starting clone point with a color close to the one that should appear in the area you want to clean. Change the starting clone point to some place near the clone area as you make it wider. Remember to use different brush sizes to make your work easier.
Use a fuzzy brush, and combine single clicks with a few click-and-drag.
The area looks much better...