Working on ancestry.com allows people the chance to receive the assistance of hints from other people’s public trees. However, one must make every attempt to verify the hints with actual documentation. Otherwise you will not only be creating false information for yourself, but also spreading false information on any ancestry tree you make public. While this might not seem like such a big deal, many genealogists loathe people spreading bad information. To reiterate, placing false information on your public tree(s) will become a source for bad hints for everyone else.
Those ancestry trees I create for adoptees and birth parents are set as private and unsearchable until I am confident that what I have assembled is true. Whenever you create a tree and are not sure you are confident everything on it is credible, on your family tree page, go to “Tree pages”, “Tree Settings”, and then click on the “Privacy Settings”. On that page pick the bottom choice, “Private Tree” and place a check mark next to, “Also prevent your tree from being found in searches.” This will ensure that no one can grab bad info and spread false information outside of your reach.
There is no way to contact Ancestry.com and claim you found bad information on another tree, and request that it be removed. They consider this medium open for individual discretion. Who’s to say what’s truth from fiction? Maybe the other individual has yet to post the proof and simply knows because they have intimate knowledge of the family they published information about. There are no rules, nor would it be easy for Ancestry.com to police thousands and thousand of public family trees.
There was a time you had to change your private tree to public for AncestryDNA to compare your DNA and trees with other’s you are genetically related to. That is no longer necessary. You can keep your tree private and still attain matches and estimated/predicted relationship ranges.
I am always a bit leery when I see a hint from a tree that has over five to ten-thousand plus people on it. Especially if the individual has an account that is less than a year old. That suggests to me that they simply clicked and accepted every single family tree hint and never bothered to add sufficient documentation to prove each individual. Be wary, and know that bad information may lead you down a rabbit hole and eventually to brick walls where absolutely zero information can be relied upon to help finding biological family. Imagine contacting someone, asking them to perform a DNA test, and then later finding out the tree you built was false. No one likes wasting time and money. So please be a responsible genealogist.