As you say, there is no illegality. And I cannot really see how someone would be in a position to bring any civil action, e.g. for defamation or invasion of privacy. A person going out in public effectively licenses all onlookers (or photographers) to observe, record and comment - again assuming that nothing defamatory results. And publishing a picture of someone in particular clothing together with a critical comment is not defamatory if 'fair', particularly if the person remains essentially unidentifiable or is so well-known (such as a celebrity) that he or she has effectively given up most rights to privacy in the absence of harassment.