One of the most reliable signs of foundation distortion is a fireplace chimney that has rotated away from the house structure. What usually happens is that the foundation heaves in the middle area of the slab. This makes the slab surface become shaped like an upside-down bowl.
If the masonry fireplace chimney is outside the house
If the chimney is outside the house, it will pull away from the house. I have personally seen a situation where there was a 12 to 14-inch gap between the chimney and the house. It was a foreclosure. The house was a structural disaster. I remember that someone had taped off the entire area at the rear near the fireplace. A really large gap is a clear indication of a safety hazard and someone had taped the area off with caution tape.
If the masonry fireplace and chimney is inside the house
In most cases, the framing will restrain the chimney rotation so that it is hard to see.