I used to think that the date a coupon expires, it has become expired, and expired coupons are worthless. But after being more frugal and using more coupons lately, I have never had one refused on the day of expiration. So this 6 am expiration is clearly designed to be misleading, unless Pet Smart is unaware that it is common practice to accept coupons on the day of expiration. Maybe they thought they were being generous by six hours. I doubt it. Marketing people research these things.