Yes.
This really bothers me. I'm just a beginner in the world of family history research but sometimes I feel like slapping my head at some of the family trees that pop up under hints in Ancestry.
In one, it actually had both my parents names in it listed as deceased (my parents are very much alive and in their 40's) with 6 children! I humorously contacted the person to ask them if they knew a big family secret I didn't and where where my 3 mysterious abandoned sisters...I didn't hear anything back for a few months but they eventually came back to me and said they were sorry and deleted things off their family tree.
For me, I do look at other peoples trees because they may have had access to information I haven't come across yet. So I get really excited when I see someone else has my furthest back ancestor and has parents for them. If it's not apparent where they got their information from I send them a polite message asking them how they got back that far...only to be really frustrated when I get a "Uhhh...well I just counted back twenty years and then attached this Knox in a similar area because they have the same name as one of the kids (when the name is John)". I've got one person whose got all the kids in a generation right, but then has the father listed at different addresses in different localities all over Durham, Scotland, Berwick, Newcastle and Northumberland...without the wife or kids, with a different occupation and different named parents every 10 years. It boils me because really, it's not too hard to compare information on a census and if you have the kids names, surely you'd be looking to see where they were? And bingo - there's the father listed at the same address! It's not rocket science!