I get that this means something like "You don't look it" or "You/I can't tell", but in English there is a difference in the connotations of these two expressions, in my opinion. For example: "I'm an Arab" "Oh, you don't look it!" Is fairly neutral. But to me, "Oh, you can't tell" kind of sounds like "Oh, you're doing a good job of covering it over/hiding it." Is לא רואים עלייך neutral, or potentially offensive? Also, do people ever say לא שומעים עלייך, for example if you can't tell from someone's accent that Hebrew isn't their first language?