The issue: tenant is an elderly man, a smoker with a dog and doesn't want to move.

My question is should I have all the tenants who are month-to-month fill out new applications and send them through the whole process, or just sign new leases and let sleeping dogs lie? 

I have a property manager who allows the tenants to breach areas of the lease; eg, pets, unauthorized landscaping changes, unnecessary repairs, etc.

I have stayed in several vacation rentals with kids and a dog and always treat the home with respect and leave it in a pristine condition.We had a group of 5 including kids over the weekend who left crumbs all over the house, food stains on sheets. 

I have an applicant for a rental house who has a 3-yr-old 78lb German Shepherd who is an emotional support dog.

I saw the opportunity for this apartment primarily because it had a fenced-in back yard (great for dog owners) and the apartments are both 2 bedrooms and in decent shape.

I don't bird dog them, if they have always delivered for me. 

At that point cash flow is top dog and any appreciation is an unexpected bonus.

dont let the tax tail wag the dog.. flipping remotely is HIGHLY risky.. 

Renters insurance, pet fees and policies around pets and their responsibility to care for them, late payments and terms around that, ability (or not) to sublease or short-term rent the property are a few off the top of my head.