A common trait among my superiors was you either had a drug and alcohol program, criminal record or atleast one diverse.

Software is a common question on BiggerPockets.

They also said i needed to account for common space electricity?

When you are having VAs call sellers, their most common statement is "I want to talk to the investor."

Common locations for supply lines to fail are where male threaded galvanized pipe is threaded into brass or copper valve and fitting bodies  (due to galvanic corrosion)  and hot water lines will rust up so badly as to start restricting water flow or begin leaking a decade or two before the cold side fails similarly.   

And this is a good, common sense rule.

As far as occupancy limits enforcement does happen but it’s not super common and every case I’ve heard of for enforcement is due to neighbors complaints  typically noise or too many cars.

It is pretty common to have IRS liens and government liens like mowing, demo, nuisance, etc. 

The more reading that I do about the subject, the more that I hear that your experience is a common one with online auctions.

Pigs get fat; hogs go to slaughter.