I think that shows why you shouldn't rely entirely on professional genealogists. Since the increased interest in Family History and related television programmes, quite a few people have now advertised themselves as experts, just because they have done their own and a few other trees. Some are very good and admit if they can't find things,but others unfortunately, as shown by Rosinish, make mistakes. These go unnoticed as most people who have hired a professional just accept what they are given - why check it if you've paid someone to do it?
Genealogy is a fun hobby and getting someone else to do the basic work takes that fun and the sense of ownership away. I think the only time I would consider using a professional is if I was stuck on a specific area where I had no way of getting access to records. Even then I would be very careful who I chose.