The thing about secret cosplays, in my opinion, is that if you're doing a super secret no-one-has-seen-or-done-this-character-before cosplay, who's going to know what character it is in the end? It's pretty much all about what people KNOW and are familiar with, and characters that people are FAMILIAR with have most likely been done already. Only the real diehard-of-the-series fans might to be REALLY impressed.
Probably about 90% of everyone isn't going to know how to make chocolate, but everyone knows the Hershey's brand name, and that they make a few different chocolates. Same with Naruto, Inuyasha, Ranma 1/2, Kenshin, and many others. Everbody knows the brand name anime, and that they have different kinds of characters, but 90% of everyone most likely won't know (or maybe not even care) about the other characters or any secrets behind the name.