Brianyi, I pretty much agree with tirediron's suggestions. It was a good catch on your part and you made good use of what you found.
I only disagree with the straightening of the horizon as an ALWAYS or even an 80 to 90% that the rule must be followed. It is not a must. It is all about what you want to present. If you took the shot and did not mind your frame and it was an error on your part maybe. But if the hill is there, gradual or not it, You must decide how you want it to look and following the way that "99%" choose is not always the best way to pick a winner.
Think of it this way, the more your image mimics everyone elses frame the more your shot has to be that much more perfect to win out over all the Joe Blow's "cookie cutter shot 101" technically speaking of course. Stir it up!
Rules, rules, rules.
Unbending, set in stone.
Rubbish.
I have to agree with Bitter Jeweler and Ansel on this one.
"The so-called rules of photographic composition are, in my opinion, invalid, irrelevant and immaterial" - Ansel Adams
I have plenty of OCD friends, including my girlfriend. I tend to ignore them when they get a little too anal for my liking.
Farrah ~ As for finding one that the specific rule we are discussing "works" for, that is pretty much subjective. What works for one may not work for another. And if you are the type that tends to discredit others work with replies concerning their level of expertise or lack there of, then a vote really won't work very well now either. So it's pretty much a mute point. (Not saying that you are Farrah, just saying
if your were
)
