I've never even considered the idea of detergent building up on towels, but it makes perfect sense. (clothdiaperaddicts.com)
If your diapers smell of ammonia from detergent build up you should strip them before putting them back on your baby. (ampdiaperstore.com)
Most sources suggest washing with less than the recommended amount of detergent, to avoid detergent build up on your diapers. (believemidwiferyservices.com)