SusanH- I schedule my gym time and work-out time for mornings and then I come home and clean up before running errands. I don't do my hair before hand so I rarely to never run out for a quick errand, and afterward I'm a sweaty mess so again I don't grace the public with my presence.
BUT... I do admit that on a day that I am lounging at home (it's usually jeans and a hoodie) I will run out for that gallon of milk or loaf of bread. I actually don't currently own any long yoga pants... I work out in short pants. But when I find a pair of flattering long black knit pants, I won't hesitate to buy them for loungewear.
I have to confess that my worst offences are to Home Depot. If I'm planning a day at home painting, I will throw on junk and run in at 6AM to buy my paint. I think nothing of running back over there during the day for anything that I realize I need. Last week it was in shorts,a tank top and baseball cap.
In defense of those who do run errands in gym wear, I just think it's just realistic. We're not talking going out socializing or to a party. We're talking picking up dry cleaning or a few groceries, right? We are busy moms juggling a lot on our plates. Working out has become a normal part of our lives and I see nothing wrong with appearing in public on occasion before or after said workout. Make up for it the rest of the time, and don't feel guilty when you do stop in at the store looking less than catwalk ready. Just my humble opinion