I just picked up a gorgeous 1977 Les Paul that has been sitting in a closet for 20 years.

Having been used, and abused, by it's last owner, there are marks everywhere that look like key marks (thick scratches; luckily most of them aren't deep) and what I learned to be called "micro-swirls" all throughout the body.

Here's an album with pictures: http://imgur.com/a/fZYEm#0

I've read that people use 3M, meguiars, guitarscratchremover, but I have no idea whether or not these actually work.

I watched http://www.youtube.com/watch?feature=player_embedded&v=R7r7CHn6Pkg, and it makes no sense to me how it could possibly work that well... Won't the cleaner remove a huge amount of the nitrocellulose finish, not just the part with the scratches??

My question is, how do these cream-like substances remove only the scratches on the finish and not all of the finish it touches, and, if it does work as demonstrated, would it successfully get rid of most of the scratches in my guitar?

I know I won't be answering your question, but quite honestly I'd leave it like that, I think it gives it more character and a backstory.
Ayy there
I concur- that is a nice looking guitar, as-is.
Sturgeon's 2nd Law, a.k.a. Sturgeon's Revelation: “Ninety percent of everything is crap.”

Why, yes, I am a lawyer- thanks for asking!

Log off and play yer guitar!

Strap on, tune up, rock out!