Stinky diapers can occur if soap residue builds up in your diapers or your diapers just did not come clean. All you need to do is wash them again. You may want to check the rinse water to make sure you do not see suds. If you do, keep rinsing and use less detergent in the future. If you see suds in the rinse cycle, your diapers are being washed with too much soap. You want your diapers to be rinsed in clean, non-soapy water. This will help prevent build up and keep the stink away!