I'm suprised no one said to ask the breeder more questions before jumping to conclusions about the cleanliness. Ask if there is a reason the enclosure isn't clean and if this is a normal practice for their tubs. Ask about their husbandry practices.

For all we know they cleaned them immediately after taking the pic, and didn't realize how much of an impact that has on potential buyers. Maybe it was just temporary enclosure for the picture. The only thing that picture tells you about the breeder is they have one enclosure with a few urine stains that may or may not be a permament home for BPs.