Several years ago, I made a "discovery" of the maiden name of one of my children's ancestors--a lady born about 1790 on the East Coast.
The discovery was easily made (and documented) through comprehensive indexes that had been created to records that previously were not indexed. Manual searches would have taken years to locate the information.
I have blogged about this person and her maiden name and how the connection was made several times. I've written about her (and her family several times). The blog posts with sufficient citation information are easy to access.
There are twelve matches for the husband in the "trees" at Ancestry.com. Not one of them has this maiden name for the wife. At this point, the discovery is not new. The problem is that the maiden name is not in the published genealogies on the family.
And the problem is that most of the trees contain information copied from other sources.
A quick google search would locate information on this female. I've actually gladly shared the information with others.
Are you only relying on the trees?
It's a good thing I'm not.