Yes, I did notice one of the pics is a stock picture of one of the newest castle, and the other pics are of old castles. It could be a fraud, but my other thought was, if these people were not the collectors and didn't really know or care about playmobil, it might seem like a castle is a castle; what's the difference, and so just put generic pictures up. They probably know nothing about steck and systemX and that some sets have more value than others and that it would be so important to know which castles are for sale.
If someone is thinking of bidding, you could email them for better pictures or a more detailed description. It would probably become evident whether it was a fraud or not.