How Old Is Too Old To Dress Like A Tween?

I've been dating Katie for a little over 3 months and usually she is OK is what she wears but recently and on occasion she dresses in these totally inappropriate clothes for her age and body. We are both 33 and the thing is I think it's time for her to dress a little more conservative. She wears these shirts that expose her chest bigtime, she wears super tight leather pants when going out, super tight shirts, crazy thick makeup...she looks good when she doesn't try to overdo it.

When we go out and she is done up the wrong way, I hear the snickers of people around us. They are laughing and I try not to let it get to me but it does because I know it's about her. I forgot to mention that she is a little overweight when she goes out. This doesn't mean she's overweight - it just means she wears pants and shirts that are 2 sizes too small. Her pants suck in her stomach and she gets a mushroom top and it is enhanced by the too-tight shirt riding up.

I really like Katie and she knows I do. This is just because I want people to see how others feel about people that wear clothes they shouldn't.