During the ancestry blitz over the last few days, I found a new-to-me type of ancestry error.  It made me absolutely furious.
I am not using the real names here, but this is how it goes.  I have a Peter Schmidt on the 1901.  I know he's there because I have found him before.  I wanted to check a detail.  This time, when I searched, he was nowhere to be found.  Fortunately I had saved the census page number etc., and entered that, and then he popped up.  The reason I had not found him at first was because ancestry, in their great wisdom, had decided that since he was a boarder, that he should now acquire the surname of the householder.  So his name is now Peter Schmidt Bakerman, according to them.  I couldn't believe this.  To go in there and change what was right, in order to make it wrong, I just don't understand this.  And, by the way, there was no "Do" or "So" or anything like that after his surname on the enumerator's list.  Yes, I have sent a correction, but how many of these are there?  Not a hope in hades of finding them by their real names, as most of us don't know in advance who was boarding with whom.