Buying Before Tax Lien Auction

I am a newbie from Dallas and this forum is awsome. I have learned more here than any other course I have bought. Thank you all for taking the time to write all this and sharing your experiences and knowledge.

I havve a question regarding buying before the action where the investor try to negotiate with the delinquent owner before the aution.

Would this be a good stratety if the property is not free and clear of mortgages. If the owner quitclaim the property to you, would not you have the responsability for the mortgage if you buy before the auction. Hhow can the owner quit claim to you without the lender calling up the note if the loan is not assumable, or has a due on sale clause.

I would appreciate any comments.

Thank you.