And remember, any tree is only as good as the researcher who has compiled it. And don't be misled by thinking a tree which quotes 20 sources for a person is better than which quotes 2, 1 or zero. If all those 20 are for the wrong person, but just happen to have a similar name, they are meaningless.
I find Family search trees are the worst because they can be changed at will by anyone.
I am looking at a tree which has my great uncle on. He had the unusual forename of Hungerford. He is on a tree with his siblings, including my grandfather, who had the unusual name of Heber. On this tree my grandfather has been called Herber and 6 sources have been quoted. On every single one of them his name is correctly spelt as Heber, but the person who added him to this tree has been so sloppy they can't even copy a 5 letter word correctly.
For Hungerford it is even worse. The person who created the record has his name correct, but for some reason in 2012 his name has been changed to Charles. There is not an individual's name against this change it just says Familysearch. Reason for change: Change made by authorized support staff or as part of an update. So a tree which was correct has been randomly changed to be incorrect by FS. They now have a Charles Eltham born England in 1887 on the tree. And of course people will copy this without doing their own research - thinking because it's on FS it must be true. If they had put his family nickname as an alternative, I would have understood it, but no-one has and I can't be bothered, because no doubt someone would say I was wrong and delete it. Source 1911 census, when lodging with his future father in law - obviously they only knew him by this nick name and recorded it on the census