A cat is definitely less stressful, but not trouble free.Cat food left out overnight invites roaches into the house.This I did not experience, but a friend who is a fellow landlord did - a tenant flushed kitty litter down the toilet and caused a blockage in the drain.One time I had to replace a central AC system, tenant had the cat in a bedroom, with door closed. 

Rv antifreeze in all traps and toilet bowls .  

Since your tenant decided it was ok to pour grease down the toilet I am going to assume this is a low income type property?

Recently a Sheriff Sale bidder told me of a property where the exiting owner took a sledge hammer to every wall, every granite countertop and cement to every drain and toilet. 

Just because so and so says, he wants to flush his job down the toilet doesn't mean that's the best suited strategy for me. 

Both seem like money in the bank to me.It seems to me that we're investing in land here (there is not much of a price difference between a water heater for a 500k house and a 120k house or a call to unclog a toilet - in fact, those numbers work against House 1 - and usually a majority of the difference between a 500k house and a 120k house is the dirt it sits on) and if that's the case, aren't we aiming to leverage as much money as possible to buy as much land as is possible, in the long run at least, and have some tenants make the payment for us in the meantime? 

New toilet?

It really is laughable.There are much better investments for a lender where they could stay liquid and collect 4% versus loaning on a hard asset that may or may not pan out and perform.Lenders price in risk for a reason.

And I'm not trying to pay $300 to replace a toilet.

Do your tenants take care not to cut the surface or place hot pans on it?