Any thoughts on this method?

I don't think you have taken into account the little things for maintenance like gutter cleaning 1 or twice a year, pest control if needed...i keep a termite bond on my properties etc.I'm not saying its not a good deal(I dont know) but I do know that your cost will be higher than what you have stated here.

LOL  just like during the gold rush it was the hardware stores and bars that cleaned up.

I've scoured the MLS for about 8 wks now and found several "potentials", however I'm not finding any success yet in striking deals via this method. 

Currently tenants go off site to do their laundry, I plan on cleaning out the basement and adding coin operated laundry and installing storage cages for the tenants to rent if needed.  

The garage tenant is really upset and wants me to pay to clean or replace any damaged belongings. 

First, I cleaned house and worked on my own for a few months. 

It will need to meet all fire and safety codes per your local building codes.Done properly a secondary unit in a SFH is the best method to generate positive cash flow on a otherwise underperforming asset..  

That is to say, when am I going to have my cleaning lady text and say, "We don't have any more _______ and we've got six guests arriving tomorrow." 

Always consider the angle of your advice/"research" CPA wants clean Audits and does not want the IRS saying he filed that return incorrectly and that's wrong.. now some employee working for you everyday will advise you on how to make things better for them everyday and so on.