Loose joints - Ridiculously easy to fix at a point that I don't even consider them a factor. A 2 minute job.
Repairing chipped paint - easy fix on most figures unless its on a large metallic surface (like binaltech). My Sunstreaker was severely chipped and now I cannot even notice where the chips were.
Chrome wear - The only thing that cannot be properly restored, only improved upon from a worn look by using silver paint but it will lack shine. However that magical chrome paint could be a solution to that.