As stated we are what we eat. IMHO flavor is directly related to more than just the feed inputs but husbandry methods also. In short a happy, healthy, "farm" from the soil on up to the farmer makes for superior table fare. With that said, are there feed stuffs that influence meat characteristics? Yes.
If one looks into the French production model for "Bresse" meat one may note that timing and housing are also considerations when finishing meat birds along with a specific diet.
To your question on corn, my experience is that extra corn will "fatten" all age classes of chickens. Corn is an energy rich feed. If the bird's intake of calories exceeds their daily energy requirements a portion of the excess calories are stored as fat. This fat can have a "corny" flavor if the ration is heavily corn based. Not all corn is equal thou. Flint corn is not field corn, is not popcorn, is not flour corn, ect.
As for apples, they too are diverse. Not only in their available nutrition, but flavor. These differences affect feed acceptance by the birds. I have watched chickens refuse to eat some apple varieties until they sour or the maggots are discovered in the rotting fruit. While the same birds ate every windfall under other trees greedily. To the point of flavor I would claim that a sweetness is gained from HEAVY apple feeding that is detectable in taste and aroma. The fresh apple doesn't "fatten" birds when fed alone because the fiber content is too high and the birds gizzard to small. There is a lot of sugars present but not enough usually to "fatten" birds on.
As to finishing out an animal to the liking of my pallet, I like a pastured bird (14-30 weeks depends on breed and gender) that has had heavy clover grazing with plenty of insects in their growth weeks. Take this bird and confine it for 10-14 days in cool/shaded housing. While confined, feed a mixed ration of sprouted BOSS, sprouted oats, & fermented cracked corn mash. 1:3:6 respectively.
