I've been to some islamic classes and in some of them there are sisters who don't wear hijab.
Well the teacher didn't point them out or anything but rather he said everyone is on their own "journey" or transition towards being better or worse. It is not our place to judge them in such things for we don't know what is in their heart.
There are some people who say that it is the inside that counts and not the outside, yes the inside is important but so is the outside!
Your outside reflects what is in your inside. However if you are a "bad" person who wants to be "good". Here's a tip, make the easiest change first. Change your outside, and your inside will follow. You will notice that your behaviour will be better when you dress better. Of course, we cannot overlook that actions are by intention. So if your intention is to just fool people then obviously it doesn't apply.