Disclaimer: If you find yourself saying something nice to a working mom with the best of intentions, that's a great thing and you, my friend, sound like a nice person. However, in my experience, being a working mom can often involve lots of thoughts and feelings (in my case, some super-sensitive ones) so it's ever-so-slightly possible that your kind observations might not land the way you intend for them to. And while I would argue that the very fact that you're considering what not to say to a working mom speaks volumes about you, many of these examples aren't exactly cut and dry.
I mean, you're probably not going up to any working moms you know and shouting, "WOW, YOU ARE NOT WITH YOUR CHILD, HOW COULD YOU?" If you are, this would be a different conversation (one that I'm probably not the best person for, to be honest, because it sounds like you're a real handful to deal with). But your comments — however well-intended — could still strike a nerve you may not even know is there. Good news, though! This is the Internet, and that means we can have a totally healthy, mature discussion about working moms. Here are a few common culprits (illustrated with animal gifs, because they don't have to worry about a J-O-B) when it comes to things you might think are compliments for working mothers, and why they might not work from some people at all.