Inaccurate shading on object I am relatively new to Blender so please excuse me if this is rather amateur! 

The bottom of my torus has poor surface quality, I have scaled the vertices down for a smaller (variable) tubular radius all the way around the torus and at the bottom the surface quality is awful, with inaccurate shading. Any ideas as to what is wrong and/or how I could fix this?

Thanks,
itsanate
These look like inverted faces.

Check your Face Orientation through the Overlay menu.
They should all be pointing outwards (blue color).  

You can recalculate them through:
Mesh > Normals > Recalculate Outside