If a face is badly discolored, all with one color or shade, its not hard to change that.
1) Go to the freehand selection tool and pick out point to point selection.
2) Using the tool, pick out an outline around all the disolored flesh.
3) Go to the layer menu, and pick out "new adjustment layer"
4) From the new adjustment layer submenu, pick out color balance
5) Play around with the color balance until you get what you want.
When the color of the flesh is suitable, pick ok (to put the color box away), go back to the selection, right click (to knock out the ants aroound your selection) and see what you have. If you see that your selection needs improvement, or have other issues with your completed work, do it all over again till you like it.
Each color has to have its own selection process, so if the area has multicolor problems, you have a lot of work to do!
This is a good exercise in Paint Shop Pro 7 & 8.