Don't think it necessarily makes you look older/washed out but the overall look needs to be good (I mean the skin on your face,neck, chest if it's showing), the make-up you use and the quality of your hair.
I see quite a lot of "older" (ie not 20s/early 30s) women here with hair that's practically white and they wear it with strong block colours - mostly black, sometimes a lot of red which I think you can carry off quite well.