Evaluating information on the early Crails

Family info collected by historian/genealogist E.E. Barton in Pendleton Co., KY [available on CD] includes a letter that offers the following tidbits [2nd-hand] from a Crail lawyer/researcher in LA:

1) John Boggs Crail's mother was Lady Campbell, daughter of the Duke of Argyll.
2) John, on his father's side, was a direct lineal descendant of the Duke of Marlborough.
3) John's father was a prominent landowner, owner of Castle Crail in Scotland.
4) John arrived in America in 1763 and served two years with the 12th Virginia Regiment during the Revolutionary War.

Cool stuff, huh?
1) John Boggs Crail was the son of Thomas Crail Sr. and Elizabeth / Jane Wilson. Unless the missus had an earlier marriage to a Campbell back in Scotland, that Argyll connection is shot! The parents posted for her on Find A Grave were from Massachusetts - that is also a bit suspect. Value of info: marginal, at best.

2) John's father, Thomas, was reportedly born in Scotland about 1720. Thomas' father has been identified as various Creels, Creals and Crails. You'd think the family of the Dukes of Marlbourogh would keep better records of their male line! Value of info: marginal, at best.

3) According to Wikipedia, Castle Crail was in ruins by 1563, there wasn't much to own. Since the castle had been in ruins for about 160 years, by the time John's father was born, we can eliminate that bit. The odds of a prominent land owner cashing it all in for a gamble in America, are slim at best.Value of info: less than marginal.

4) John was born in Maryland, not Scotland, in 1745. He did serve in the 12th Virginia. [Rev. War pension file]. Value of info: adequate.

I don't know where Lawyer Crail's info came from, but someone in the family had a desire for a "prominent family" and invented same!