If you own things free and clear, then you're obviously not over-leveraged (or leveraged at all!)

The drawbacks are that repairs/modifications are expensive due to the house’s age and that I have to clear everything through a historical society as a result.

Hello,I am rehabbing my first property (owned free and clear) and my contractor wants to purchase it through seller financing. 

Frank Guzman to answer your question - when a borrower/ owner quit claims the deed all they are doing is transferring ownership but it does not mean the title is clear for the new owner.

Public records and publicly recorded leans looked clean on this one and his claims of title being clear and prepared seemed to align with some quit claims filed last year moving ownership to just his name from a multi-partner situation.

If the Buyer records his/her contract against the property, and later either defaults and/or decides not to pursue the option, then you still have the cloud on title until the Buyer provides you with a release or you file a lawsuit to clear up title. 

Sometimes we just trade information: "That title isn't clear, I saw bad cracking on the back wall of the foundation of that place, FYI, that one was just postponed."

To be clear this is not your modern boxed office building but one of different spaces built at different times having smaller units.

I take all complaints very seriously and had my plumber clear all the drains from the main line (>$200), and they then complained about noises, smells, etc.... 

I would do what Henri suggests above and this is a really good time to clear out any marginal performers, the market is high now and poor performers will follow the market down faster and deeper when that happens.