I don't think blunt or honest appraisals are necessarily mean spirited. But they can sting a bit. It's not always possible or helpful to sugar coat advice, when it's asked for.
I personally stay away from fashion or make up advice and would withhold a so meant if I thought nothing good could come from telling someone how I,really think they look. But on relationships, communications, coping,with behavioral health issues, I feel I have something of value to and will be direct if it's merited...but usually in private.