Don't always aim for perfection .... good results can be achieved from very bad initial sources, as I have shown ..... the following is a good example:
After
Top Tip Both the pictures above are reduced from the very large version on the web .... when working with a very large picture, consider resizing to a smaller version when you have finished the repair ... the very large pictures highlight those blemishes that only hours of work might remove, and lets be honest most pictures (like the one above), aren't worth that effort (which isn't guaranteed to work).
.... but after I had cleaned and repaired, and then reduced in size again, then the end results are very good, and without having to waste hours on all the scuffs that it would take ages to fix up.
of course, where you can use floodfill (you can't always do so - but thats
another post), then you can get rid of background scuffs, and this is the final version