.....and even worse are the ones that SAY SOMETHING. 
ie. today. i was on a packed bus with screaming, teething, 16 month old DD. nb, she was fed, watered, clean bum, so i knew it was her teeth.
nothing was calming her down and i honestly think she was picking up on the fact it was stressing me out big time that she was crying, which was making her worse. i could feel all the eyes burning into me, and then this woman said to me, "awwww, is she thirsty?" I wanted to reply, NO SHE IS NOT FUCKING THIRSTY YOU NOSEY BASTARD WIND YA FUCKING NECK IN, DONT YOU THINK IF SHE WAS THIRSTY A DRINK WOULD CALM HER DOWN!! 
:o
in reality, i snapped, "no, she is TEETHING actually!" loud enough for the whole bus to hear, whilst fixing said lady with a withering superv1xen glare.
felt quite sorry for her actually
but i would just NEVER comment on a screaming baby or child, and if i see one while i am out i certainly dont stare and/or judge.