I was researching my family and on one side I got back to about 1800 with censuses and such. Then ancestry started showing hints by showing me other family trees? How accurate do you think those are to use? Because if so I tracked my one side back pretty far.
Family Trees, as with all other information which is online should be double checked by the interested party for accuracy. People are human and make mistakes so my advice is to take what you need and then check the sources to confirm the info.