I have often wondered about this and I guess it depends on the original picture and what one wants to convey. A good illustration of what is pleasing to most people is the great difference in opinions (so far) of my Glowing and Glowing 2
Personally I prefer the original, but that is because in it I see what I saw - a pretty gift of garden flowers on my kitchen table in the sunshine, whereas the "improved" version is a place-mat without any soul. However, in this case, the time spent in PSP seems to have paid off as far as vote opinions go.
I wish I had the talent that many others have, of producing pictures that do not need any enhancement.