Being new to the business, you're likely to: severely underestimate the acquisition and rehab costs, not budget (or at least budget enough) for unknowns, skimp or go overboard on finishes for your market, overestimate ARV, holding time, construction time, get taken for a ride by a contractor, and on and on.

So, with that being said, and the former being written, either I am in an awesome market with tons of potential to create a successful business, or I am setting myself up for disaster because of things unknown to me.  

What if the LL is in the midst of foreclosure, unknown to you?

Of course the hypothetical buy can have pluses too but it is an unknown and another location is less efficient for maintenance and costs.

I guess it’s fear of the unknown.

As a statistician venturing into the unknown brings up all sorts of risk-related thoughts and possibilities, most of which I have limited control.

My advice is to get started, don't let the fear of the unknown scare you.

Unknown at this time if the house needs repairs soon such as a new roof.

The reason I would adjust the repair expense would be due to the unknown condition of that potential 4th door.

There is just so many unknowns when it comes to auctions.