There are now so many millions of people registered with Facebook.com that the search function of that site can give interesting hints and probability information whether a name exists or not.
Jorah passes this "Facebook test" because the site lists something like 30 people registered with this as their given name; Yoreh doesn't pass, however.
Maybe such a heuristic is not scientific enough for some people, but I found it very helpful to weed out non-names and to answer questions like the one at hand.
Rene
www.AboutNames.ch