The first time I washed my hair with conditioner was an accident and I was surprised that my hair did suds up.
Conditioner has some detergent in it, but it is gentle. A few weeks ago, I was having trouble rinsing some hair product out of my hair. Instead of letting the water run over it for a long time, I decided to plug the sink.
I was amazed how quickly my hair rinsed out. I started plugging the sink every time I washed my hair. The running water rinses the back and the sides while the standing water rinses the top and the ends, using less water. Saving water, saves money.
It also let me see the suds rinsed out of my hair, giving me proof that washing my hair with conditioner does clean my hair without stripping it.