There are many things that can be found on a roof just like in the two pics above. Both can be fixed before inside damage has been made for the price of a tube of caulking.
If the nail heads are not caulked over and the pipe has no caulking around the pipe water can run down the pipe or under the nail head and over time the drywall on that nice newly painted ceiling will start to show water staining and mold.
With every home you are looking at buying it would be a wise idea to get the home inspected by us at Red Bear Home Inspections to give you a report of the condition of the home so you don't run into costly renovations.