The more units, the better because a vacancy would not force you to an unpleasant leave, especially with one or two units where the percentages are  different greatly on vacancy. 

Check the public records, what liens are on the property, what violations, back taxes, water bills etc.If buying directly form the seller (using an agent), make sure you have a lien and title report to protect you from buying a property with unwanted liens or judgement s that will have to be paid before getting good title.Other ideas for you that may help you understand the auction business better:Contact auction companies (always talk to the principle of the company).Do some research of that company; what do they primarily sell, stuff (assignments), antiques, coins, real estate, foreclosures etc.attend their auction, get to know themAt my company we have auctioneer associates, their job is to run leads and to create leads that we can sell at auctions.

FSBO will likely care and might say something unpleasant or sub-optimal. 

Thus you'll probably be stuck trying to sling a bunch of unwanted inventory to a small subset of people who would buy from you on sites like craigslist or your investor meetings or what have you.

I am willing to be there will be nothing but unpleasant surprises for 5 years. 

We're seeing Vacancy Rates tied to Class of property.Lowest vacany rates are Class A properties, rates rise on Class B & C properties.Realistically, capital expenditures aren't usually a factor for the first 3-5 years of ownership - as long as you have a great inspection, so there's little chance of an unpleasant surprise.

A poorly renovated property, or a disengaged property manager, will make for a very unpleasant experience.  

I'm certainly not trying to dissuade you from getting into the VR market, it has brought us fantastic cash flow, I just don't want you to be unpleasantly surprised down the road. 

Oh gosh, these memories are unpleasant :(

, but one thing caught me by unpleasant surprise: Property Taxes for rentals are crazy 2.1 - 2.3%!