What to expect at Sheriff Sale if modified loan is underwater?

[Cin Ng]

I'm new to all this, but what if it looks like the loan was modified and then defaulted on? What is bank bidding protocol (in Cleveland area)? It seems most cases are bought back by the Plaintiff bank.  Could there be any FNMA involvement? I was looking at a past case in the same town and saw that FNMA bought the property at the full appraised value, and the minimum bid is only 2/3 of the appraised value here. I'd like to buy my first home at a particular sale, but am trying to figure out if I would be wasting my time attending the Sheriff sale. Thanks!

Also, what implications are there if the owner filed chapter 7? Would there be a high chance of other liens that may still be tied to the title then? And why would an HOA be named as a defendent?