I definitely wouldn't want my daughter to send around naked pictures of herself. However, if she did, that wouldn't make her a bad person, as "slut" connotes.
I don't think it connotes that to everyone. At least, to me, it only suggests high promiscuity, which isn't a bad thing in and of itself. Nor is it necessarily true in this case, but to those who formed our worldviews before omnipresent recording, sex-themed pictures of someone intuitively imply promiscuity. We'll just have to get over it; the world has changed.