Unless it doesn't make sense for the setting (like motorcycle gear in a medieval RP) or very 18+ material, I don't see why you have to change a character's attire just because the GM doesn't like it.

As for personality, I like laying down the groundwork for my OCs to develop.  And then I see my OCs taking a slow turn away from the original intention and it's usually too late to realize.
For example...
[i]Umbreon makes a villain OC that's supposed to be unpredictable and tyrannical.[/i]
[i]Many pages later, Umbreon realizes that the villain OC turned out to be an affably evil character that follows a gentlemen policy.[/i]
[i]Umbreon wonders what the f*** happened there.[/i]
I get that sometimes the characterization of a character can change from the original intention, but this has happened to me many times in my RPing career.