At the Bay Area Photo Club's August Honor's Night this past Tuesday I got busted for using a transplanted sky in the image below....
The only problem with that is that it was the original sky! I did add an exposure correction layer in PS3 to lighten the mountain bluff and foreground because the original image was under exposed. I then added a mask with a gradient fill to the sky to eliminate hot spots this caused in the clouds. The mask was just a blunt force dark-to-light quickie from the top of the image to about the bottom third. I did not actually take the time to mask the horizon line.
There are no rules in the contest against using composite images in fact it happens quite a bit. I suppose the issue is mainly one of believability, if it looks real the issue is mostly mute.
I'm not faulting the judges for saying what they said, it's there job to report and comment on what they see. I'm just curious about what you think?