I'd like to get rid of the folks who are not paying, because they have also been violating the lease in other ways such as removing the smoke detectors.

Smoke signal????

Hi,I'm a new landlord and a tenant in one of my units has clearly tampered with the smoke alarm.

for me if I jumped back into rentals depending on what class they were.. for C class where the tenant basically wont do anything proactiveI would do it quarterly  that your changing filters checking smoke detectors  and our going to pay to replace light bulbs..

Replace batteries in smoke alarm.

Furthermore, there is the potential of extensive smoke damage in the same airspace and that has to be mitigated properly. 

One of the best things I did to build wealth was buying a foreclosure that was ready to move into except it needed paint (smoke smell) that was a 5/3 and rented 4 bedrooms to professional women and lived in one.

Here's the quick overview of my numbers and projections with more detail in screenshots of my excel spreadsheets:Purchase Price:  $365,000Price Per Unit:  $60,833Two-Family:  $121,667Four-Family: $243,333Rehab Estimates:  $60,000 ($10K/unit) Estimated After Repair Value:  $575,000Loan:  90% LTV (of purchase price) @ 12% interest for 6 months with 2 points paid on exitProjected Cash-On-Cash Return:  29.35%Projected Internal Rate of Return:  51.02%Here's a picture of the current rent roll (two units were vacant) and my projection of the rent rollCurrent Rents:  (more details considering the numbers don't tell the whole story)Two-FamilyUnit 1 (2BR+):  VACANT - son-in-law lived here and moved out prior to closingUnit 2 (2BR):  VACANT - empty when I walked it... he was "finishing" itFour-FamilyUnit 1 (2BR):  $200/week H&HW included - one bedroom is painted entirely black, multiple windows are broken, and other weird things...Unit 2 (1BR):  $780/month H&HW included - only "normal" tenant in the buildingUnit 3 (Studio):  $150/week H&HW&E included - complete hoarder... floor to ceiling with junk except for a small path from his bed to the bathroom and the fridgeUnit 4 (Studio):  $155/week H&HW&E included - smokes in her apartment without a care in the world... had a lit cigarette while I was walking throughProjected Rents:Two-FamilyUnit 1 (2BR+):  $1,400/month (OWNER-OCCUPIED) nothing includedUnit 2 (2BR):  $1,200/month nothing includedFour-FamilyUnit 1 (2BR):  $1,200/month H&HW includedUnit 2 (1BR):  $1,100/month H&HW includedUnit 3 (Studio):  $1,000/mo H&HW&E includedUnit 4 (Studio):  $1,000/mo H&HW&E includedHere's how the numbers broke down for cash in and cash out:Actual and projected expenses for the properties (I was given a single sheet of paper with hand-written numbers). 

They test the smoke detectors and ensure a carbon monoxide detector is present in the home. 

They did smoke in the unit and I am wondering if I should give them back the deposit or keep it.