When I first joined Ancestry all of the user trees had my family going in a certain direction that when I looked at closely, didn't seem right. I later found what I believe to be the correct lineage, and since then all of the other trees have been copying my research instead!
Now I'm not cocky enough to say that I'm 100% right, but I know it's my tree they're copying since the relevant record that I found is not available on Ancestry, or any other family tree websites I've looked at.