I take them off though I had some bags where I had forgotten to do that before. It kind of bugs me when I see them left on bags carried out - when they're at the point where they're noticeably visible and lifting at the edges or something. Kind of like how it kind of bugs me when people forget to remove the stitches holding the back pleats/vents together on a new coat. It makes me kind of want to say something to the person (politely) but I wouldn't want to disturb a stranger just to say something like that! I'm weird.