I grew up reading the comics as my dad sat across from me and clipped grocery coupons on Sunday mornings, so I've never been one to judge those who use them. There are some people who are embarrassed to shop with coupons, and even in our slow-as-molasses economy, self-conscious shoppers are still projecting their feelings onto coupon-using shoppers.
One study found that people waiting in line thought shoppers using low-value coupons were cheap, and that sentiment was carried over to the person in line behind the coupon holder. This particular study observed shoppers buying pens in a bookstore, and those who used a $0.50 discount for a $4 pen were judged most harshly, while shoppers who used a $2 coupon to buy a $5.50 pen weren't considered to be as cheap.
Coupons are all about getting more for your money — as a kid we had my favorite Breyer's ice cream in the freezer instead of the store brand carton, because a coupon brought down the cost of the name brand product. It's not much different than refusing to buy a particular item until it goes on sale, except you have to be comfortable using coupons at the register. Do you ever find yourself passing judgment on coupon clippers?