Bingo! You guys have it, its not some grand RMT conspiracy when something seems awry. It strikes me as a matter of coding. I have noticed that particularly effective players in Campaign are indeed getting lots indicative of their work.
I have put this theory out there before only to be scoffed at. However, I dual box and my second is a whm that I basically cure, buff and heal status while my main annihilates campaign mobs.
The result, (when my main is doing quite well and dominating) is that my main gets very good, comparably high lots where as my secondary
tends to get poorer lots. There is a still a randomness to it as I've seen but I clearly detect a favor of success. This is clearly not a scientific study by any means but notable trends in experience are... useful.