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.  

REFUSES to EVER let us in to do our job as your prop mgr" but I know darn well that even if I live in a single fam home that I own free and clear, taxes paid, etc thus NO ONE has any "hook" on me to open up my door to let them in to do anything, if a neighbor calls the city (or in my case the village where I now reside, where things are a lot more tightly controlled than in the city of MKE, where they have all sorts of issues to deal with) if they call and say "hey my neighbor is this Bob guy who's got crap piled all over his home, he gets really drunk at night and falls asleep with lit cigarettes in his hand and he's going to burn his house down sooner or later and I'm scared it will take my house with it" trust me, they WILL be at my door soon to check this out!

@John Chan - I had a 10+ year chain smoker in one unit that I inherited.  

There is 1 smoker on the first floor and it is awful.  

If you are not a smoker and your other tenants are not smokers then it can be a big problem.If you get this lady to leave plan on de-greasing the ceilings, walls, ductwork etc. to get the film of smoke out.Either way it sounds like you are going to be spending a lot of money in the future so plan for it now.

Walk up to them and when they are about to say something, ask them if they could spare a dollar and a cigarette.  

Many who would be inclined to fly the Battle Flag of the Army of Northern Virginia (this is most likely the flag you are actually concerned about) will also display the symbol on their car, their key chain or, perhaps, on their cigarette lighter.