Except for white ones, they are disgusting. But colourful with patterns. Wonderful.
I had an old cotton skirt that was falling apart. I decided to make some handkerchiefs so I cut it down the seams and I cut some squares. The first set of squares I cut 12"x12". These made an okay size, so I tried the next one at 18x18. I think I would like 20x20 if I ever did this again.
Then I put my small hemmer foot on the sewing machine and did a narrow hem. It's so easy with this foot as it folds the hem over for you. No ironing down the hem.
But I did iron after to set the stitches. These are working great. So much better than using new fabric which I always find too stiff and scratchy for the purpose. Used fabric is much nicer, but I do recommend 100% cotton or Linen or a cotton linen blend.
I took old T-shirts and cut them into "wipes" for cleaning my little girl's bum. I also cut up an old terry bathrobe for wipes, too. My husband also uses squares of old T-shirts as covers for his kombucha. I've also used my husband's pants and cut them up and turned them into maps for scavenger hunts.