Well Joe @Merijeek ,
Its mostly Scaling in Object Mode, that’s causing problems. With Meshes, you can simply Apply the Scale after the fact, but with Curves that gives often unwanted results (as you’ve seen).
Transforms, done in Object Mode, Transform the Object’s Coordinate System and Scaling a Coordinate System ‘distorts’ it.
That’s why Scaling is best done in Edit Mode. Rotating (and Translating), on the other hand, is usually best done in Object Mode.
Scaling in Object Mode can be useful, when you have Linked Duplicates (copies, that all use the same Mesh Data, ie.: Vertex Positions and so), for instance one rock, that can be placed around the Scene, Rotated, Scaled and so, all in Object Mode, to make it look less like just one rock.
This will all become much clearer with time.
