I went through a phase a couple years ago with the "Rack Grade" Greek Garands where I cleaning and tweaking them -- I got all my squadron buddies to plunk down $295 for one, and then I worked them into being decent shooters. Most of them simply needed to have their bores cleaned. They looked terrible upon first inspection, and a cleaning jag did nothing to improve them. I had a homemade electric bore cleaner that really did the trick, and there were nice bores underneath all the crap. Similar was true for the rest of the rifle; they had caked-on bearing grease and cosmo everywhere, and after some elbow grease and Hoppes they cleaned up into well-used but better looking rifles.
Nearly all of them had lousy replacement beechwood stocks that were mis-shaped, or beat to death, or under-sized, or whatnot. I found a place on the 'net (Doug's Stock Pile) that had old GI walnut stocks for sale for something like $15. The wood on these things was usually GREAT, but it was under a coat of paint or a ton of old dirt and grime (they were usually ex-Korean).
A trip through the dishwasher almost ALWAYS returned these stocks to a beautiful walnut base, and then I really enjoyed the sanding and BLO treatment to beautify them for use.