The perception of sarcasm is heavily dependent on the intonation, the facial expression, and body language, and even the relationship, of the one delivering it, to the one receiving it.
I have been with my wife for over 40 years, and I totally understand her delivery.Sadly, she has no clue when I deliver. To placate the situation involves waaay more time then I am willing to give up, so I find it best not to overwhelm her with my insensitive boorishness.
So when she asks if she looks good in a certain dress, I say yes dear, that dress looks very nice on you.I don't tell her it would look just as good on a camel. It's a great dress,really. I don't tell her it would look good on anybody.If she chooses to go out in that dress, hey,let someone else tell her it's two sizes too small, 4 inches too short, and it makes her look fat.