I always figured that Sakura wore her gloves so that when she goes all SAKURASMASH™, her knuckles doen't bleed/get cut.

Writing Sai mean is just as OOC as writing him happy, or sad, or any other emotion, really; if he doesn't have a firm grasp of what it means to express his emotions, why would he purposely be an asshole? He's so impressionable, I doubt that he really knows what he's doing.

Naruto!fandom keeps me entertained. Most people just treat it like it's their own personal novel and change up character's looks and personalities when it suits them. It's crazy. :/