I think Daniel is being nice.That looks like mold, as others have said. Since this is an auction house, are you suggesting that it will be impossible to perform a detailed investigation of the property prior to bidding? If so, I would strongly consider purchasing a different property. Mold always requires moisture, relatively warm temperature, and a food source. The wall is the food source, but where is the water coming from? That is a question I would want a definitive answer to before I put up hard cash for a property.