There are times where you will not have a choice when a repro panel just doesn't line up as it should. As Vikki said, if you are putting it on, but sanding it off to repair dings or to crisp up a body line, its part of blocking. If its properly adhered, properly sealed, and fairly thin, I would think anything more about it. Now if you are filling holes with it, thats a different story.
I know that washing and waxing my car with the present condtion of my paint is like polishing a turd.....but it's my turd and I want it polished!