as you know....And it used to be a lot easier also.We used to be able to go to the Dept. of Transportation and get a copy of drivers licenses, which of course have addresses, as well as DOB.We even got non-driving ids from the DOT.We used to get new postal addresses from the PO for $1 each.We used to get birth and death certificates from the Bureau of Vital Statistics.We used to be able to get letters to prisoners.We used to be able to inquire if a senior citizen was a resident of a specific nursing/retirement home"USED TO" is the key phrase.

@Mike Flatow You're talking about buying the Tax Certificates, which is just essentially loaning money to the county.  

A vacant 40 unit is highly likely to need a LOT of work to start renting.Otherwise, the seller would be renting out the building to generate income and raise the sales price.You will need deep pockets for the purchase and to have any hope of financing, you will need bids & estimates to determine the total cost to get full Certificate of Occupancy.

From all I have seen there is much confusion about what is legal and ok versus those who risk being shuttered and seized without proper licensing, certification and city oversight.

Why would a renter pay $100 to an online "therapist" to be diagnosed and get a "certificate" instead of just visiting their family doctor or a counselor? 

This year it might be nice to give them a gift certificate to a local business like a coffee shop or cafe.

It takes 14.5 years (if you're lucky) from undergrad to board certification to practice in my specialty, and I feel like that is barely scratching the surface.

Every year in Detroit and nabourghing cities you need to get a rental certificate, and every year they threw at us a large list that cost so much to fix.

@Ayesha N Everett that'll be mostly Class B as long as you aggressively screen applicants.Also, make you get your Certificate of Compliance from the city as the 36th District Court is getting testy with landlords that don't have it and appear for evictions. 

Last year I sent Christmas cards out with gift certificates to a local pizza place.