Speaking from experience, albeit with a different breed, I too would walk away. I have a 2 year old lab who is a very nervous dog. When choosing her as a pup we saw the mother who was delightful and so friendly, but did not meet the sire. We got her from a gamekeeper, recommended to us, but not a reputable breeder as such.
Her nervousness resulted in fear agression and we have had to work very very hard to overcome this with her. She is now so much better and continually improving but it has taken 18 months of upset, hard work and not to mention the expense of behaviourists etc.
Lesson learnt for us, always use a reputable breeder and don't be worried to ask lots of questions, and walk away if your instincts tell you to.