My first Blender addon - "Massive Boolean" lets you combine a ton of objects at once, by running cleanup steps after each boolean operation to avoid mesh degradation. : r/blender
Clean Up a 3D Scan Using Blender : 5 Steps - Instructables
Blender 2.8 - How to fix your text (Cleaning MESSY vertices) | TutsByKai - YouTube
Blender Beginner Tutorial Part 1 - Effective Mesh Clean Up (LeoCAD imports) - YouTube