Also, I'm curious to hear – how does renting to C class tenants modify (if at all) the criterion for accepting an applicant? 

If purchasing all cash do we just accept a smaller COC return?  

If you choose to accept it, make them apply and pass your screening, add them to the lease, and charge extra rent to make it worth your trouble.

Seller shall furnish a copy of a prior owner's policy of title insurance or other evidence of title and pay fees for: (A) a continuation or update of such title evidence, which is acceptable to Buyer's title insurance underwriter for reissue of coverage; (B) tax search; and (C) municipal lien search.

I had an offer written up but knew if I submitted it too soon it would look like a low-ball offer and probably not get accepted, last day I was in town the price dropped and I threw in a full offer and asked for full closing costs.

I sent a low-ball offer, and we went back forth but ended up getting 30K under asking accepted.  

If they choose to stay, make it clear they are accepting the property as is.

This is where the big money is I have heard if you're willing to fork out more money and accept a higher level of risk.

If the seller accepts your offer than you do the full due diligence investigation during the option period.  

Not sure if this is acceptable, or was in 1991.