For many years, I couldn't find a clan associated with my surname (McCaughtry). Recently, however, I bought a surname history from a website and it states there was a Clan MacUchtry of Garvie in the Middles Ages.

This brings two questions to mind:

1) What are the chances the information in this kind of surname history is accurate?

2) Is there a source I can use to find a Clan Crest for a little known clan? My guess is Clan MacUchtry of Garvie died out a long time ago.