There are trees on Ancestry that have my maternal gran's elder sister dying on exactly the same day as my gran and at the same address. Clever that seeing the elder sister died 16 years before my gran. I know I'm right as my gran lived with me, my parents and my brother and she died when I was 8. Her elder sister died 6 years before my parents married and at least 3 years before my gran and my mum (still single at that point) moved into our address.
I've tried telling one person but they've not corrected it and I really can't be bothered to tell the others.
I've also got my g.grandfather's alleged parents shown on numerous trees, but although they were parents of two sons (one died) of the same name, they are not the parents of my g.grandfather. I don't know who his parents are, I just know they're not the ones everyone thinks they are. I've no idea who the tree owners are, as they don't seem to have any connection to my family, so I guess they're just people who go around collecting trees. If I look at the trees to see where a connection can be made, there isn't one.