Here is the situation: I am weight painting on a symmetric mesh, and have put a lot of time into part of the rig. I discovered that there is bad topology in a certain section of the mesh that needs to be fixed by deleting vertices. However, if I delete any vertices, the vertex group symmetry option (Vertex Group X under the Tool options) completely breaks, and weight on the opposite side of the model will spray across random locations when I weight paint. This happens even if I edit the left and right sides of the mesh in exactly the same way. Symmetrizing the mesh with a function like Mesh > Symmetry would ruin the UVs.
What is there to do if you need to edit your mesh without breaking the symmetry of your weight painting?