Only list those ingredients that are apparent to the senses. It doesn't matter what went into it as much as what they are going to be judging it as.
There is no rule that I know of that says you have to list everything you put into a batch.
It will be judged, as you say, with respect to what the judges taste and smell, so only list those things that are apparent.
The guidelines clearly state to list all fruit used. So there is a rule. There have been many ethics questions lately at comps I have been involved in. Situation.....a Russian Imperial Stout is entered, the brewer states that he added coffee and chocolate to his brew. How do you judge this? Is it misentered, should be a cat 23 or fruit veggie, or spice beer (not sure where coffee and chocolate fit in)? Or since the guidelines call for those flavors (even tho they blame the darker malts for contributing) judge it as is ignoring the non-conventional ingrediants?
If a brewer entered a Russian Imperial Stout then there should be no place on the entry form or on the pull sheet given to the judges to state that he added any coffee or chocolate. How would the judges be informed of that? If it were stated on the entry form, then perhaps the category should have been "specialty" instead of RIS. Those ingredients, if not mentioned
, may add some complexity to the beer, which could be a good thing.
OK I just referenced the bjcp guidelines for melomel and it says, "entrant must specify the variety of fruit used" not "list all fruit used." I take this to mean that the judges need to know what they're supposed to be judging as opposed to what the recipe was. It does not seem to me to be a requirement to specify all the fruit as much as it does to tell the judges what fruit should be apparent.
Please don't get me wrong. I don't think anybody needs to brew "to style" to have fun in this hobby, but there are some guidelines to follow to do well in competitions.
Ethics have more to do with blind judging than recipe formulation.