They won't appreciate at all, tenants will not be good, will not be in good neighborhoods, and chances are that the rehab is shoddy.

An accountant could explain it better than I could but if you think of Goodwill, they are a nonprofit organization too with millions in operating costs...

I also let long term tenants slide sometimes on the deductible as a showing of good will.  

I'd rather help my good tenants and generate some good will in the process.

This covers 99% of people and they appreciate the goodwill and thoughtfulness. 

Argued this one with them for two years but I'm still paying that damn $60/month.So I'm trying to build up lots of goodwill before I ask the city water department to remove those other three meters, ha.

This offer is extended as a gesture of goodwill, allowing you to exit gracefully prior to the eviction process commencing.

But, how good will you be at betting what those gradings will be in 5-10 years time? 

Here's the quote from the Michigan statute:"Real estate broker" means an individual or business entity that, with intent to collect or receive a fee, compensation, or valuable consideration, sells or offers for sale, buys or offers to buy, provides or offers to provide market analyses of, lists or offers or attempts to list, or negotiates the purchase, sale, or exchange of real estate; that negotiates the mortgage of real estate; that negotiates for the construction of a building on real estate; that leases or offers or rents or offers for rent real estate or the improvements on the real estate for others, as a whole or partial vocation; that engages in property management as a whole or partial vocation; that sells or offers for sale, buys or offers to buy, leases or offers to lease, or negotiates the purchase or sale or exchange of a business, business opportunity, or the goodwill of an existing business for others; or that, as owner or otherwise, engages in the sale of real estate as a principal vocation. 

These guests are usually good, will not dirty your place, overall will be less headache etc.