I have an Aunt who is basically exactly the same. Anytime she sees any of our family/friends etc, she always has some offending comment to make.... She regularly tells my mum she looks old, fat, tired or things like "did you not bother to do your hair/did you dress with the light off this morning". She does it to everyone she meets.
Surfice to say - now at age 60 - she has virtually no friends, none of our family - or extended family ever see her if we can help it...... and the only real person in her life is her husband - as even her children don't really want to know her anymore as they cringe everytime time she says something (because it always seems to be the 'wrong' thing) - and she even says irritating stuff to them.
That being said, it's just the way she is.... and she will never change. I just don't enjoy being anywhere near her - becuause to be honest - the things she says - I don't want to hear - and she doesn't really have to tell me. In a way I feel she has some sort of complex - and gets enjoyment by telling people their imperfections.