It will not be a deal-killer, but knowing what the impact will be in advance is crucial.  

No HVAC is the killer....I am doing conventional right now on a 575k flip....

So start exploring other options for yourself now so when you find that next killer deal you can execute it.  

Or you can try and find an absolutely killer deal that will just appraise a good amount higher than you paid for it.

Slow down a bit and network with local investors, find a mentor and get yourself a killer deal that you can tackle within reason.

And if this was the only time. 2) Ask for an Elevation Certificate  (link here if you don't know what it is)  3) try to get a DECLARATION page (same link if you don't know what it is) reason being a savvy agent can port over the rate if the seller is getting a killer rate due to government subsidies. 4) you can either shop the NFIP and private flood market to make sure you are getting the best price and best coverage. 5) make sure you are working with an agent that understands flood insurance (ask how many flood policies they have under 700 - Not an expert) 6) Google search "Lloyds of London flood insurance" know there is more than one option and you can hire a firm to shop them all or do it yourself. 7) Google search "Private flood Insurance" Know there are a great number of alternative to the government program (NFIP) and they are not all equal so again working with a flood expert could make this option a much easier option. 8) ask your loan officer or realtor if they know of anyone that really understand flood insurance and an expert agent that can make sure that the loan closing isn't delayed due to incompetence in this field. 9) let me know if I can help.

The house is full of cats and cat poop and is completely uninhabitable (I got a killer deal on it, and I knew what I was getting into.) 

That's a killer deal, was it a commercial property?

Churn is the frequency with which you lose tenants, either because they want to leave, or because you're forcing them to leave through an eviction process churn is the real killer of profit and is not covered as often by BiggerPockets or other forms as it should be, in an area such as st.

Although a few of them may actually do a loan for a slam dunk killer deal, if they do, they’ll end with most of the potential profit too.