I wondered about this recently. I recall seeing a photographer that likes to take some sort of animal skull with him and 'place' it in his landscape shots. I started thinking about how much I manipulate my compositions when shooting. I can think of once I added a leaf to a bench scene, as it really needed it. Then there was that golf ball shot, I stuck it in a particular position and turned the brand towards the camera. I've cleaned off paths where there were too many leaves, added backdrops to a flower shot as to remove the fence from the background, turned a champagne glass, asked a guy to hold that strawberry under the chocolate fountain, placed a shoe on the path...and it goes on and on. Now that I think about it, I 'manipulate' probably 50-60% of my images. Until I started thinking about it, I didn't realize how much I did.
This question doesn't apply to any type of portraiture, as that is entirely a 100% setup.
So, how much do you guys/gals 'improve' your composition by moving, adding, deleting from the scenes? Anyone out there a apply a 100% journalistic approach and capture it exactly as it is?