"Verify" is a pretty strict criteria. More pratical is that if it requires an explanation, it will always require an explanation and will bring the value down. Look at a lot of them. Many you see at shows will have dubious characteristics. Buy a couple of good books to start with. Find a reliable dealer. Ed Tinker is very honest about his stuff. So are Tom Armstrong and George Anderson. Others will pipe in on who they have dealt with.
|