I've seen a knife goobered up by a gun show sharpener. It was sad since the knife had sentimental value. My friend got his $3 refunded.
I had two customs sharpened their makers, both 20+ years of experience and one was a master smith. Both used a grinder and took off more metal than needed. One returned it not as sharp as I would like and I fixed it.
I sent a knife in to one manufacturer to be fixed and they sharpened it too. Changed the tip profile on a traditional slipjoint even though the edge was fine to begin with...they were just trying to be nice
My lesson is power equipment and knife sharpening is dangerous even in the hands of professionals. Learn how to sharpen and take the time to do it right. If you care about scratches, practice on beater knives first.
I had two customs sharpened their makers, both 20+ years of experience and one was a master smith. Both used a grinder and took off more metal than needed. One returned it not as sharp as I would like and I fixed it.
I sent a knife in to one manufacturer to be fixed and they sharpened it too. Changed the tip profile on a traditional slipjoint even though the edge was fine to begin with...they were just trying to be nice

My lesson is power equipment and knife sharpening is dangerous even in the hands of professionals. Learn how to sharpen and take the time to do it right. If you care about scratches, practice on beater knives first.