Sometimes issues with the roof are visible from the ground to prospective buyers, but some things are only uncovered by a professional inspection. Issues that can arise include brittle shingles or improperly installed, missing or damaged flashings.
Problems with the Foundation
Cracks, slopes, and sticking doors and windows are all issues that can be discovered that relate to the foundation. Many issues can be fixed with caulk and epoxy but it is always best to leave the diagnosis to a professional.
Overloaded panels, outdated wiring (for example aluminum wiring) and amperage mismatches are examples of issues that can occur with an inspection of the electrical system. There is always a fix for issues, but never underestimate the importance of the electrical system being up to code. If an electrical system is not up to code, it could be a fire hazard and render the property uninsurable.
The best step to keeping your roof long lasting and your foundation dry is by having gutters in good working order. If you have gutters that leak, do not drain properly or are not channeled properly away from the house, you will have issues in the future. They're not too expensive to repair when you consider saving the health of your foundation. So if you do uncover issues, don't skimp and put it off.
Shabby Interior Details
The most common thing that inspector note is the general condition of the carpet, paint, and walls. These are mostly aesthetic things, but it is important that these details are brought up to modern day expectations of style and cleanliness to preserve the highest value of the property possible.
Poor water pressure, slow draining drains, water stains on ceilings and loose fixtures such as faucets and handles. These are normally not expensive issues to fix and with a little know how can typically be remedied by the homeowner.