Could be the seller knew it was worth close to nothing after he messed with it. I agree with Russ about a problem with one of the lens elements, or maybe bad processing. Here is something you might try. Make sure the battery is in the camera, and it is mounted on a tripod.
Cut out a piece of plastic from a blister pack the proper size to cover the film frame in the camera, scuff up one side with some fine sandpaper, and open up the camera and tape it on the frame with the scuffed side towards the lens. Then cover the meter window with some black electrical tape. Make a target using electrical tape on a piece of white cardboard about two feet square, and place about ten feet in front of the camera.
Open the shutter, and hold the button down (a locking release cable is good for this). That should give you a few seconds to look at the image on the plastic with a magnifying glass or loope to see if you can get it to focus.
If you can't see it come into focus, then remove the plastic, and look through the elements of the lens to see if there is anything directly in the center of the light path. Operate the aperture through it's full range to make sure all the blades are moving correctly.
PF