Typical for this type of article, there is no distinction made between properly disclosed investor transactions.

It is important to make that distinction, that is where you are a "Principle" in the transaction thus not brokering a deal.

Usually there is no distinction for HOAs if that agents serves more than one HOA.

I like to have three distinct pots of money, rentals that cash flow, 401k and then an after tax brokerage account in the market. 

or 2 seperate properties altogether, ie, condo conversion....thats a big distinction. 

It makes some pretty distinctive odors, though I can't tell you want they are.

Even if you turn on the light you can't make out a distinctive figure.

Different foreclosure and asset protection laws make each state distinct from a risk profile.

In our area(s) and experience (which feels more limited as time passes) a rooming house serves a distinct clientele:  a) university students (perhaps a sub-population such as international students); b) work force for a major employer (factory, refinery, mine, hospital) or c) those on the margins (those one step from the streets, the mentally ill {as governments have closed most of the traditional homes and care facilities}, the addicted, etc).  

@Will Stahl There is also a distinction between what is legal by state real estate laws vs what is allowed on the MLS.