What Not to Say About Someone's Appearance.
Don’t say: “You look tired.”
Why: It implies she doesn’t look good.
Instead say: “Is everything OK?” We often blurt the “tired” comment when we get the sense that the other person feels out of sorts. So just ask.
Don’t say: “Wow, you’ve lost a ton of weight!”
Why: To a newly trim person, it might give the impression that she used to look unattractive.
Instead say: “You look fantastic.” And leave it at that. If you’re curious about how she got so svelte, add, “What’s your secret?”
Don’t say: “You look good for your age.”
Why: Anything with a caveat like this is rude. It's saying, "You look great―compared with other old people. It's amazing you have all your own teeth."
Instead say: “You look great.”
Don’t say: “I could never wear that.”
Why: It can be misunderstood as a criticism. (“I could never wear that because it’s so ugly.”)
Instead say: “You look so good in skinny jeans.” If you slip, say something like “I could never wear that…because I wasn’t blessed with your long legs.”