I've cleaned more than a few rifles for friends. Usually they aren't in horrible condition, but, they still have fouled bores. A lot of people will be careful to wipe a rifle down after use, and run a few patches with Hoppe's through the bore, but they don't have the knowledge or equipment to really get a dirty bore clean.
I have to agree with Rapier, too: I've bought more than 1 rifle with a 'shot out' bore, and turned it into a shooter with good cleaning equipment and a bit of time and effort.
