Unwanted Stretching in Rigged Meshes

Todor Nikolov writes:

If rigid pieces of your character keep bending even though you carefully weight-painted them, then the most likely reason is Bendy Bones.

Here is a common problem: pouches attached to the hips squash and stretch regardless of weight painting.

Something related: a twisting forearm in Robotic characters. If you want the lower arm not to bend at all, you have to disable twist bones AND bendy bones.

In this video, I show a couple of ways to solve these problems: