I have judged quite a few competitions as well as entered a few. As a judge I dont even consider if the image was PS'd unless it is very poorly done. I feel with the tools and the digital domain we have to accept that PS will be used on all images.
My stance is, if it is done tastefully and it is not a false representation of the layout, than it is good.
If somebody blurrs to add depth, dodges or burns for highlighting, or clones out snails i say that is all fair game. What is the diff between the pro photographer who uses a snoot to highlight an area vs a PS tool? Nothing in my opinion. Or a blurr effect to simulate a VERY expense fast lens? Nothing.
Dont add things that arent there and it is fair game. If you suck at PS it will show and your product will look unnatural anyway.
I have given many talks on PS for planted aquariums. If anyone wants to look at my gallery i am very open about how i got the results i did.
oh, and as far as camera mattering, it doesnt. Lenses and lighting matter most, the camera matters least.
Here are two pics. One taken with a $200 P and S and one with a mid level DSLR. Which is which?