@Andrew Steffens the pool of buyers that have six figures of cash (you really need about $150k in cash to buy a $500k STR), have some subject matter expertise, AND want to self manage is even smaller. 

Get a sewer line scope and use that as a point of negotiation if you're the buyer. 

I'd love to hear others' opinions on this but I am a fan of making the house as attractive as you can to a potential buyer, even if that adds cost. 

A buyer needed, I heard through the grapevine, $100M of liquid capital to acquire them for very darned little.

Loan would have to be assumable from the bank and the buyer would need to meet all the requirements previously met by the seller.  

Your potential buyer suggesting you terminate the contract and them paying you a fee does sounds fishy to me.

Significant and sustained population growth leads to demand exceeding current supply, causing prices to rise until there's a rough balance between sellers and buyers.

Sellers are offering incentives like paid closing costs, and with homes sitting longer on the market, buyers have more room to negotiate!

Buyers could look at a DSCR loan which does take into account the revenue from the rent but it doesn't count towards the value of the property.Now, buyers could look at a business loan of some kind but I am not sure they would qualify if it is only one property and even then, the value is mostly in the property and not the possible revenue. 

If the property is not cash flowing and is due to your mortgage carry, it will most likely require a cash buyer to work (or close to it).