The World Family Tree data comes from ordinary people like you and me. FTM gives people eternal fame and $10 off on a purchase if they send in a GEDCOM. So, the data ranges from the impeccable and well-researched to what can best be described as "peccable" - family tradition coupled with wild hopes, impossible surmises and faulty logic. In my experience, the WFT data is about as good as the LDS AF - 75% accurate, at a rough guess.
The other FTM CD's - Land records, Census images, etc. etc. - come from original source documents. FTM does a great job of making old documents available to the public cheaply through the magic of images on CD's.