I once bought a ton of shirts from the supermarket because I was going to an African country and I did not want to look like someone with money. That's the only time I did it though.
Purchasing clothing at super markets can be hit or miss. I have had success with purchasing underwear and socks for myself and my family at such stores. Usually the brands for these items are the same you could purchase elsewhere (such as Hanes, Gold Toe, or Fruit of the Loom.) While some clothing items at supermarkets is actually pretty fashionable and in-season, often the quality is not great. I have purchased my husband a couple of hooded sweatshirts from supermarkets, on which the zipper broke within the first few times of wear. On the other hand, I have purchased dress pants for my husband at a supermarket that have lasted quite a long time and still look great. As is the case when shopping for anything, the key is to do a quality inspection of the item before purchasing it. If the fabric is thin, or the stitching seems poor, skip it.
While I usually prefer to buy clothing belonging to name-brands, there have been times where I've seen something cute or appealing, at a great price and have proceeded to purchasing it. I've bought things like sandals, flip flops, pajamas and t-shirts to hang out in the house.
Hmm.. yeah. My girlfriend buys stuff like that all the time. She doesn't mind where the item comes from as long as its fresh and unique.