As I posted over on DC...I seriously doubt the two product's chemistrys (hair conditioner/waterless wash) being compared here would be even remotely similar. A waterless wash needs to suspend dirt and contaminants in a solvent that will allow it to clean the surface and not leave trace dirt and residues behind. Hair conditioner will leave a waxy coating behind and it is not designed to do any cleaning at all.
If people want to try homemade solutions on their own paint I guess it's up to them, but I believe that a waterless wash product specifically designed to do this type of job is going to way outperform water + hair conditioner. If waterless washes were so easy to make, why wouldn't they have been invented and marketed sooner. Hair conditioner has been around for a long time... and it's not going anywhere near my car.