I, too, am looking for my great-grandfather, John Quincy Adams. He disappeared after 1895 from Fauquier Co., VA leaving a wife and six children. He was not on the 1900 census as living with the family. My grandfather, who was 13 at the time, would never speak of him.
One of the rumors [there are many] is that he showed up at the St. Louis Worlds Fair with a new wife and family. Someone who knew him from Virginia supposedly saw him there. This is pure family legend, I have no idea if there is any truth to it.
However, the place, dates and story fits. I have a photo of my grandpa John for a comparison if you have one of yours. My John Quincy Adams was born 1854 in Fauquier Co., VA. He was quite handsome and looked younger than his years. He was a wheelwright and carpenter by trade. Yet one of the family legends indicates that he was selling books when he disappeared. The "traveling salesman"!!!!
I'm anxious to hear back from you as this has been the great family mystery for over 100 years. Boy, wouldn't it be great to solve it!