You are so right Baileybelle -- it is always possible to get those unpleasant surprises. That's why I personally would not rent a home or condo direclty from an owner unless they had a track record in writing of past guests, or unless I had more than email contact (some phone conversations, for example) with the owner. Beofre we rented our vacation home I directly emailed one of the guests who had entered a positive comment on the online guest book.
There is one direct from owner website, orlandovillas.com, and its sister sites, which is run by a very nice family who "verifies" all of the listings, meaning they make sure the owner actually owns the property by checking city records. But more important than the "verification", which is pretty minimal, is that the owners on this list seem to have formed a "virtual" community and they look out for one another and feel a real pride in maintaining certain standards. You can tell this on the discussion boards there. So I would feel confident renting from that website without seeing past guests' comments.