10,000 btu would be your minium for a family of three, take into account how many people and pets will live there.

Scratches will show & if a person had pets that's bound to happen.

In my area, renting SFRs, not allowing pets would cut my pool of prospective tenants by probably 2/3rds, but not allowing smoking cuts it by maybe 10%.  

Another real cost is holding costs while not being paid and damages to the property--and by damages I don't just mean retaliation, I mean deferred maintainence, pet damages and crazy decorating choices which is what I mean in 3) above...losing control.Also, an owner held mortgage, even seasoned, is not very liquid and if interest rates go up, even less so.  

.- Some people do no pets and no smokers policies as well.

You're a grownup, after all, not a small child or a pet.  

Pit bull "comfort pets" and "need" to smoke "medical" pot beside a unit with a child with asthma are just two of the newest treads.

No conviction or eviction in the past.4. max of 2 pets allowed but with $250 pet deposit for each pet.5.

Make sure the tenants know that their pets and children should not touch the traps.Find out how the rats are getting in and eliminate that.  

You could get lucky with a tenant who wants to live there for years, or you could strike out and get continual one-and-done leases.Have you ever read Stephen King's Pet Sematary?