Question of the Day

Question: When is it appropriate to make comments to someone about their appearance in public? Comments can sometimes be seen as insulting. Do people forget themselves or do they not realize that what they say can be construed as an insult.
Case in point: A complete stranger walks up to you and says," you look tired. Your eyes are all bloodshot...or do you have allergies?" Do you take offense to this comment and view it negatively? Or do you perceive it as someone making an observation and respond politely? If someone you knew made this comment to you, would your perception be that they are concerned and truly want to know?
What compels a person to make comments about someone's personal appearance in front of others? In my opinion, if something I'm going to say may be taken in the wrong context and I could end up embarrassing the other party, I won't say it. I won't make observations to them like, "you're really breaking out," or "you've gained weight, are you stressed out?". To me, those types of comments are hurtful and unnecessary. I think it would only draw unwanted attention to said person's insecurities.
I've been on the receiving end of comments such as these in the past and, to me, they are NEVER appropriate.