I worked in the textile industry in the late 60's, in the dying department where I worked we used a water softener, but actually it was a water soluble lubricant applied to the cloth before it was made into garments, this was to prevent the high speed sewing machines from overheating and keeping the needles cool by reducing the friction just like a car needs oil for the same purpose, so this is how Fabric Conditioners come about, this substance attracts dirt like most lubricants. Reading a label on a bottle of Lenor recently, they say it is harmful to Aquatic life, also not to be used on children's sleepwear (in that case why use it on their daywear?) added to that it makes clothes more flammable, plenty of reasons there not to use it at all.
I use a Supermarket own brand Non Bio washing liquid and no FC this leaves my clothes smelling good, OK they are not so soft but less greasy and less likely to attract dirt, Please Mums don't waste money on Fabric Conditioners.