I bought a house in the inner city like that. Some things off the top of my head: wiring from a wall switch to the ceiling light was wired with an extension cord. Not a heavy duty orange one, the brown twisty kind you would use for Christmas lights. Knob and tube wiring that was capped at a dead end (no junction box) protruding from a hole in a closet. At the panel everything was updated romex so it was tied in somewhere. Never figured out where. Wires were sliced together in the kitchen ceiling without being in a junction box, squirrels got in and would cause it to short out.

An outlet tester costs $10 and will tell you if outlets are wired properly.