You are doing the correct thing by vacuuming the carpeting after the professional treatment. 

You NEED to defer a gain to get the initial treatment that later allows for the 10 year deferral.

And to be eligible for 1031 treatment you must have created that real estate with the intent of holding it for investment use. 

Credit Karma shows me 775+ while the mortgage broker s ore was in the 690s.

The biggest issue is the houses sell as UNfurnished.It would require a $30-40k downpymt to buy these houses but then another $30-40k to decorate & furnish them nicely (this includes all furniture up to & including window treatments, hot tub, etc.

@Eric KullingIf it is very faint, you might be able to do ozone treatment on the house and get rid the smell altogether.

Hi Kim,They make pet proof carpet padding, and rental carpet typically only has a 5 year life span.Your CAPEX for the carpet should recover some of the cost of replacement if cleaning (and ozone treatment) don't fix it.Given the unlikelihood (in many cases) of actually collecting damages in excess of the damage deposit, renting anyplace to anyone (pets or not) without pet proof padding under the carpet is just asking to lose money.And the Carpet CAPEX should be built into your rent.Pet damage can be expensive and not always recoverable from the tenant, so it's best to assume pets will be in the rental even if the lease says no pets, and install pet proof padding.Some cats (unfixed) spray walls, sometimes just the litter box makes the smell and when that's gone, the smell is gone, but with dogs they all tend to have "Accidents" on the floor.

Or is there a different treatment from when it’s considered a second property?  

@John KimThe tax rate on a short-term capital gain is the exact same as ordinary income.What you're really worried about is SE taxes.It's unlikely that this will be capital gain treatment. 

Since that's not real estate it doesn't qualify for 1031 treatment.