I'm not addressing Ancestry.Com other than this, they are the biggest theif on the internet, they stole 90% of what they charge for, and no one knows where they got it from not even themselves...
I don't belong to the LDS church, but they largest geneological resource on the internet. There census records, and digitized marriage, birth, and death records are an excellent source.
There ancestrial files Are the result of interviews with direct family members in the early 1900's, Most of the times there are no other sources and they have to be used, What I do to improve there reliability is to find the 1790 to 1850 census info that can be extrapolated back to confirm it. I would hate to see thousands of profiles damaged by someone trying to source them when there are no other sources.
Many of the EARLY ancestry.com sources are the stolen ancestrial files. Wili needs to have a policy on converting all these Ancestry.com sources back to there original source files, documenting them, and then going from there.