I live on the Ohio side of the PA/OH line, I have thought about making my way over to PA to dig some milks. What Plumbata said about it being a good place to find valuable milks is very true. Especially the cop top bottles and war bond milks with intact writing.
Milk bottles that are dug tend to have cloudiness inside of them. It is rare to dig even a common milk bottle without it having case wear and cloudiness. The smaller size milks tend to survive much better, I think this has to do with not allowing as much watter in. The more water in the bottle over time the more deposits will be left on the inside.
I keep all of the minty milks I find. I have many that I have brought home, few ever clean up. I think it goes for any bottle that when it is upside down in the ground it will probably not be sick or cloudy. Most milk bottles have very little value so tumbling them is rarely worth it. Last ditch effort for me is 0000 steel wool to try to clean them. Case wear can not be helped but rust stains can easily be removed with muriatic acid. The acid will not remove deposits but may loosen it so that the 0000 steel wool can remove it, usually there is nothing you can do but tumble.
