+1 to all of the above.
Especially in BJCP competitions - invariably you are going to be brewing "someone else's recipe"...... that is the nature of a style guideline. There are only so many ways to brew a bo-pils, or ordinary bitter - the odds are if you have something truly unique, you have brewed something out of style.
If I am looking to brew a style that is somewhat new to me, I always start in one of two places - I either start with the recipe out of "Brewing Classic Styles" or I start with a recipe from the NHC Gold Medal Database....... generally I will tweak them over time a bit, so I suppose they are a bit different from the original at some point. Ultimately, though, it is process that is being judged. 10 people could brew the same recipe and end up with 10 different beers due to process, temperatures, water, quality of yeast starter, sanitation, etc.
I would say that if you find success with some source of a recipe it is good to give some credit where credit might be due. I use recipes out of "Brewing Classic Styles" - I also recommend people buy the book anytime someone asks about a good source of recipes. I have good success with british ordinary bitters in competition - my recipe is based on "The Innkeeper" off of Northern Brewer - I recommend the kit to many people. Or, if you find the recipe on a forum or know the source - my guess is those people would love to hear that it did well for you too.