Why 3D model shape is distorted when rotating?


A question I’ve been avoiding… it’s time to face:

In the picture you see an original model and a distorted model, once I rotate the original model.
I have many models from different packages, and this one is changing it’s shape, which is not so good for my VR simulation as the user picks it up and starts looking at it.

What would cause this change of shape? all the models went through blender-unity pipe, but I bought them, and they’re as is.
I’ve played with some model settings as suggested in an answer, but it kept changing.


It looks like its parent is scaled.

An object’s scale is applied to its matrix before rotation. So it’s scaled first, then rotated with its changed scale.
When an object has a parent, that parent’s position, rotation and scale are applied after the object’s own transformations. Meaning that the object is rotated first by its own rotation, and afterwards scaled by the parent’s scale. Imagine taking an elastic cube, putting it on one corner and then pressing from staight above. This is what seems to be happening here.