Manufacturers repair team turned up to renew a skin damaged (by the airline MX) after the aircraft skewed during jacking. The damaged section (about 22 feet by 6) was attached top and bottom by lap joints and butt joint either end. This "team" (probably an assortment of connies and old hands) proceeded to abrapad all traces of paint and protection from said joints in order to reveal the rivet and hyloc heads.
A few things:
1. some of the burnish marks looked about 10 to 15 thou deep !! seriously impairing damage tolerance
2. steel fasteners attacked in this way leave microscopic residue embeded in the alumimium which causes corrosion
3. the countersinks need re-making as the rivets will stand proud - this risks knife edge stress.
4. 2024 has a 2 thou layer of pure ally as a protective coating - now rendered useless.
Always paint strip or media blast to reveal rivet heads.
I was there to oversee the insurance job - needless to say I reported this to the manufacturer, insurance co, owner etc and was ignored. Money changed hands, a 8110 (equiv) issued and off she flew. Fussy Brit I guess. If I'd done that when I was an apprentice I'd have been out the door.