You can easily identify good quality jeans by turn a pair of jeans trousers inside out. You just need to check the quality of the stitching and sewing. For good quality jeans, there should be 8-10 needles in an inch. And then, check the jeans accessories they use. For example, the zipper; there are many levels of zipper quality. The best jeans zipper is YKK, SBS etc. Lastly, smell the jeans; good quality jeans smell clean and fresh.