Are there any red flags/additional information I should look for when assessing a tenant's bank statement?

The upside is definitely there.Your assessment of B-/C+ neighborhood is probably accurate, though I would lean more towards B-.  

You can even go further on to assess customer satisfaction levels to make determinations about the perceived quality of your product. 

Gross Rent 10,800Vacancy @6% -648Net Rent 10,152Prop Tax (180/mo) 2,160Insurance (est.) 500Repairs & Maintenance(5%) 540Prop Management (8%) 864HOA (220/mo) 2,640Net 3,448Debt Service (262.61/mo) 3,152Net before consideringcapex or assessments 296I don't know what your insurance, repairs & maintenance, or prop management cost will be but I suspect these are fair estimates.

If you didn't factor that in that could make for the 12k difference in a 4 month span in a declining market.If the market keeps dropping and new inventory hits and cuts down prices even more you will wish you would have kept this buyer.Maybe get the buyer to bring some cash to closing to make up the difference or you could finance the rest but the lender might not allow that and not disclosing could be defrauding the lender.The reason is the lender will assess more risk of default if the buyer has additional payment besides the senior loan.

My suggestion would be download both a copy of the tax liens to be auctioned by the county and a list of assessment data (you may be able to download or purchase from the county or a third-party source such as CoreLogic), then match up the two lists.

Unless you are talking about small local banks or credit unions, it would be highly improbable for one to be able to get a sit down with the one in charge of making such decisions and then granting your wish.You would be better served to make relationships with the top REO brokers in your area and when they have deals coming down the pipeline, you would want to arrange access immediately following the eviction/clean-out so that you may assess the property and calculate your max offer amount.

Find out how this structure is assessed.

Brian - We've written comprehensively about those topics on the BiggerPockets Blog, and it has certainly come up many times here on the forums as well.

You should up your reading comprehension skills.