The levels weren’t alarming per say, but home has been known for “feeling stuffy”.

Your time is much more valuable spent lining up the next deal, rather than worrying about remembering to call the handy man to go change the HVAC filters and batteries in the smoke alarms.

Tenant has received numerous warnings on paying late, but at some point, landlord do not want to be  alarming and cause tenant to leave.

You WILL also have turnovers (i.e. vacancies) that require some degree of investment (re-paint, carpet,fire alarms, light bulbs, etc, etc) and while the vacancies may be short, its not easy to turn over a unit with ZERO downtime.Regarding your planned refi, I assume your 3.75% 30-year is based on an owner occupied mortgage? 

I've got alarms going off in my head like crazy here because many lenders will go up to 85% on a PRIMARY HOME....I know what you are thinking "well, we told him it was an investment property"....but what normally occurs is that once you get into underwriting and then they tell you their limit is really 85% on primary homes and it's 75% on rentals...or something like that. 

I have it in my lease, but I check and change filters if necessary when I do my smoke alarm and property condition inspections biannually.

Here are some cost breakdowns that we charge based out of Springfield MO:Window Blind (L/M/Wand) 60/40/8Toilet Seat 35Painting 1 room 150Painting 1 room ceiling 105Light Bulb 5Smoke Alarm 75Drywall 40 per 4 sq/inIf you don't know exactly what it will be then estimate high and then if you end up getting it done for less the ex-tenant will be happy to hear that they get more money back then they thought. 

Simplisafe alarm systems, which I use in all my vacant/under construction units, have a temp sensor option.

It was alarming in the beginning, but after a few weeks I didn’t even notice the horns.

I learned not to be too alarmed over an 'as is' offer.