For example. a duplex listed at $175k with estimated rehab costs of $25k (new structural beams, front porch, etc,) puts the mortgage around $200k, not to mention all of the miscellaneous issues that will appear in the near future.

The house was built in 1905, and there are what appears to be tree trunks supporting the main beam of the house in a few places. 

A local investor with a laser focus on his particular niche will always outperform everyone else, even in a mediocre market.

Get laser focused and figure out what you want to do.

After inspection, the floor joists and support beams in the basement are in need or replacement.

You should be laser focussed on that rather than worrying about buying a house.

If it's been leaky for a long time open the possibility for support beam/ floor Joist being affected and or mold.

I plan on buying 5 properties by April of 2021.The 4 unit asking price was 130, after walking through I offered 125 it was accepted.After in inspection, the following "major" issues were identified.Basement wall was caving in, inspector said there are a couple different ways, some contractors will place steel beams along the wall, or take the whole thing down and redo the wall.The unit has 4 electrical boxes in the basement all set for 100ws   Problem is the line going into the house is only a 200W line. 

@Austin Wood Foundation issues will vary by region and type (slab, pier and beam, basement).  

Many years ago when I was pressed into Executive Management of a burgeoning company charged with growth and sales I found myself getting spun-out by trying to win and keep every client at a significant cost to business as a whole, I had this "ah-ha" moment and I got laser focused on knowing and defining who we were as a company, service, team and just obsessivly being that and letting where the chips fall where they may. 2 years later at a big industry meeting I was introduced as COO of the #3 company in our major national market and got asked about what we do about those clients we loose which was very simple for me; "if your not loosing ____% of clients, your doing something wrong.