Actually if your plan was to take stuff from folks who don't need it any more it might be good to have some tailoring skills so that you can make the clothes fit better (or fit period) and repair any wear and tear so that they last as long as possible.

I think of this issue not in regards to TSHTF but related to being out in the bush for an extended period of time and having wardrobe problem. I carry a change of clothes but if something bad happens to one shirt or one pair of pants, I know I'd do a poor job of sewing together a repair...but I'd still try.

This isn't so hard to believe as I used to think it was. If I fall in a rocky area and shred a pair of pants, I have to switch to the spares. If I soak/shred/etc that pair too, I'm going to want to change especially if it's cold...the first pair could be unwearable unless I do something to fix them...not a job to undertake while hypothermia sets in. To leave them shredded I might as well leave them in the bush and save myself the weight. Either way it's in my best interest to repair those pants as best I can. Even a knee hole should be fixed right away as it could lead to further unrepairable damage. We don't carry reams of cloth and sewing machines do we?