I'm following BlenderGuru's tutorial Blender Beginner Tutorial - Part 5: Modeling
I'm trying to model a coffee cup. I started with a reference picture of the cup, added a cylinder, resized the base of the cylinder to match the cup, and resized the bottom of the cylinder to make the shape tapered.
However, when I add a loop cut to the middle of the cylinder mesh and scale that loop, the bottom edge loop becomes distorted and jagged for reasons I do not understand; it is no longer the nice ring that I want it to be.
What's going on?