I would still take the steps of the 5 day late notice to cover you, hopefully she gets you the rent by friday.Be ready to hear constant excuses.

I've called several agencies and get the same excuse every time.

The list of justifiable reason is endless assuming you properly design your screening criteria.However in this OPs case there is no reason to make excuses.

Yes they are making 1,200/month now, but they worry about  whether rent is going to come in, they have expenses such as insurance, taxes, maintenance and that occasional excuse from the tenant, "My mom died again!"  

Explanations are simply excuses for greed in their opinions.Generally you would be better off if he left and you found a new tenant to pay the full market rent from the get go.

We try to change out the A/C filters when we go over there as an excuse, but also to make sure that they are being changed out for the life of our A/C unit.

I think if his lease is all the way through August, the fact he's notifying you now he's leaving duty doesn't excuse him from paying the last month.  

If a tenant has a problem with landlord not completing essential repairs like the flooding from the upstairs unit, the tenant can file a complaint and escrow their rent payments with the city until the issue is resolved, so their excuse wouldn't work to prove they were responsible tenants put in a bad situation.  

If a deal isn't reached, that's usually when crazy emergency maintenance complaints start to pop up where you are spending 100s if not 1000s to correct, with the tenant trying to use it as an excuse to break the lease at each occurrence.On the flip side, if you want a tenant to leave, you're almost out of luck unless they want to go or they break the lease.

This is the short list of reasons why...of which many are combined, and most are excuses, to form the basis for the "why":1 - Fear of....