Oh and for what it's worth unless it is just a smoking hot deal please don't find a house on the MLS, negotiate it down a few thousand, get it under contract, then try to flip it to an investor. 

(ie.. the doors open, the windows work, the furnace works, and smoke alarms are functional with 10yr batteries).  

Envision little faces pressed against the bars through the smoke...

With that be said I can image it has no CO2 alarms, smokes or exhaust fan for bathroom.

When I charge $5 for a bulb or battery for a smoke detector don't complain.

Just purchased a small multifamily and there are tenants that smoke in their unit...my lease is non-smoking...tenants are currently on a verbal lease...any advice- they are long-term tenants- been in the unit for over 2 years and reported to never be late on rent...

In 2011 my wife walked into small 1950s cape style house that reeked from 60 years of cigarette smoke and fell in love with the property.

Don't forget that you may also need to upgrade the smoke alarm system, which may need to be tied into the electrical system (hardwired) for a legal rental property

I can understand the no pet/smoking criteria.  

Many people are more tolerant of pot than even cigarettes.