You are presuming the "seller used the cheapest labor, cut corners and and used the cheapest materials."

Again, the BiggerPockets store has some books on this topic, or you can learn about it by watching podcasts, reading blogs, and interacting on the forum.

Myself I took some class's but just started selling RE at 18 got my license while going to collage but I made my first sale in 75 and got a 900.00 commission and thought Wow.. my job as a grocery store bagger was paying 2.00 an hour.. 

It can be like the clothes nobody wanted at the dollar store, it wasn't going to be great to begin with and what was usable in some way is already gone.

When it comes to real estate, here's a general list of eligible assets and their depreciable lifespans that you should know: Residential Rental Property = 27.5 yearsThis includes any building or structure where 80% or more of its gross rental income is from residential units.That means:- Apartment buildings- Single-family rental homes- Duplexes, triplexes, and quadplexes- Mobile homes (used for residential rental)- Any kind of residential lodging facility where the primary purpose is long-term rentalCommercial Property = 39 yearsThis includes non-residential properties like:-Office buildings-Retail stores and shopping centers-Warehouses-Industrial complexes-Hotels and motels that do not qualify as residential rental propertyLand Improvements = 15 yearsThese include sidewalks, roads, fencing, some landscaping, and parking lots that are separate from the building.Personal Property = 5 or 7 yearsPersonal property used in a rental activity usually has a 5 or 7-year life.This includes most furniture, appliances, carpeting and various machinery.Qualified Improvement Property (QIP) = 15 yearsGenerally, this includes any improvements made to the interior of a non-residential building after the building was placed in service, excluding elevators, enlargements, and the internal structural framework.Computers and Related Peripheral Equipment = 5 yearsVehicles = 5 yearsNote that the land itself is not depreciable.

For example, my appliance store gives me a 10% discount, so I charge a 5% markup to my owners to make a little money and the owner still saves 5% from retail. 

Definitely screen properly and don’t cut corners!

And it's not only the homes, you also have to fortify your grocery stores, schools and anything else.

I immediately went to the project and took the contractor to the store to buy all of our supplies. 

Clothing- buy at the second hand store.