I had a black denim skirt that had that smell. I ended up donating it. A textiles scientist at our local university told me that black dyes are unstable, so other chemicals are added to stabilize them and the smell is permanent. I actually sniff clothing now before purchasing to avoid this from recurring. I also have learned to never buy denim with a high polyester content because they feel hot when I wear them, tend to bag out and worst of all, they are lint and pet fur magnets. You may have a different outcome but for me, polyester denim is a no go. I also hate tencel, too.
