I was told to never wear anything with ruffles, anything pink, and to avoid feminine clothes for job interview?

it depends on the employer i guess. just make sure you are dressed respectfully and seriously. i don't think certain colors will count against you. depends where you work also. just be feminine but serious. dress appropriately for that particular job and then looking feminine will be okay. thats like telling male teachers to not wear masculine clothing.

I hope this isn't true - why should we try to "defeminise" our clothing for an interview - is the feminine dress sense considered as unprofessional? Maybe if there is too much ruffle then it is understandable, but I'm sure a touch of femininity would surely add a touch of class.

It depends on where you're working....

In general, those things are fine in moderation. Too much ruffles, too short of a skirt, too high of a heel, a loud/obnoxious pink...things like that should be avoided, but feminine clothes are fine as long as they're not loud, crazy, or slutty(unless you're a stripper/hooker)