@Deanna McCormickThey weren't smokers.

I would send them notice of three violations. 1) lease says no pets...get rid of the cat before it destroys the property.2) stop smoking on the property or face eviction, offer to release any smokers from the lease.3) cure the insect infestation immediately.Inform them you will me making regular inspection visits and expect the issue to be resolved.Your other option, if you have no desire to inforce your lease is to tear it up and write a new one that you do intend to inforce.

We're both non-smokers (a property that hasn't been smoked in would be outstanding) who seek a 3+ bedroom (possibly 2 bedroom if there were a separate office), 1.5+ bathroom house with a fenced yard, garage (2+ car preferred) in a very safe & secure neighborhood (I will travel some for work). 

Pot smell doesn't stick like cigarettes.

They are heavy smokers and aren't the cleanest.

I've had to hold on to evicted tenants cigarette smoke-filled crap before so I feel where you're coming from @Benjamin Mueller.  

The carpets are really dirty, which might indicate a smoker.

Honestly, as a smoker I would limit it to smoking outside.

Houses for $600 or less are getting hard to find.I would rent this place to dog owners and smokers.

The only thing separating me from the other houses on the same street is a little smoker's balcony.