After luffy's trauma, marineford, sabaody etc... we really got to see a part of him that was unknown until we got the ASL flashback...
Luffy is you typical "stale" character in the outside but with unstale inside... He wants to be pirate king just to be free, he seems like a kid, but it's deeper than that, that's why he frees people that are getting bullied everywhere he goes without even noticing what he is doing. He acts on instinct but I wouldn't say it's "stale"...
Sanji is defienetly not stale also, but it's pretty easy to see why in his case because he shows it in the outside (very versatile etc...)