I prefer SFRs with no HOA too ... higher buy in cost, but generally better appreciation & tenant class, more control, more "value add" possibilities (try doing an addition on a condo :)), and no unpredictable HOA fees or assessments to eat into my cash flow.So, though some think that all that buy RE in CA for appreciation are crazy gamblers, and many in fact are, I myself am incredibly conservative, because of my multiple exit strategies believe that what I am doing is NOT gambling, and have the consistent long term track record of profits (in BOTH appreciation AND long term cash flow) to back it up.

Spitz dogs—which are, ironically, quite aggressive and unpredictable. https://en.m.wikipedia.org/wiki/Shiba_Inu

The ones that are completely unpredictable are the ones who move in crazy girlfriends/boyfriends. 

Appreciation in the near term is unpredictable and historically has many cycles.  

Extremely unpredictable and not worth the hassle when they stop paying.

Real estate can be unpredictable at times and there is nothing like a war chest to allow you to float during tough markets or make acquisitions when financing is tight.

Stay away from the cheapest houses in the worst neighborhoods despite the temptation as they are unmanageable and unpredictable. 

It provides an added sense of security for all those unpredictable situations that may occur.

Timing is unpredictable aside from looking at past cycles.

CHBO can be inconsistent, but with the $300 cost easily covered by one booking, it can still be worthwhile despite its unpredictability.