While there is no set rule when it comes to damage repair, most dealers prefer not to have damage repaired prior to trading in or appraisal. The reason is that most dealership appraisers are skilled enough to see where a vehicle has been repainted. This will raise questions as to why the vehicle needed paint and the fear that any minor damage might be hiding major unseen structural damage under the skin.
A dealer would rather see minor damage in person and know the extent of the damage, rather than wonder what if? Plus, dealers can usually get damage repaired at a lower cost then you can get it done for.
One exception would be if the dent or damage can be repaired without having to paint, perhaps via paintless dent removal.
-answered by Lee Scott, Consumer Advice Editor