看看这儿吧，

Auction has many meanings. Could be foreclosure auction, which are further divided into judicial and non-judicial. Or could be mass auction by the bank. Or even individual seller.

My understanding is judicial auction gives you a clear title, sans any senior lien. Non-judicial auction? I'm not sure. Better check 如山's post as he's an expert on non-judicial auction. So you need to know what type of auction it is.

Judicial 法拍屋真实经验

Good luck.