i use shampoo AND conditioner. i use herbal essences "totally twisted". its for people just with curly hair. my hair always looks great! i use it on my clients that have curly hair too and it works for them.
and yes, conditioner may work, because what conditioner does is make your hair shiny and tangle free. but, conditioner does not get your hair clean. it actually makes your hair more oily, and if you're using it WITHOUT shampoo, then after a few times of only using conditioner your hair is gonna get really oily and gunky and gross. :P and since it won't be clean, your scalp is really going to itch andn your hair will not cooperate since it's not clean.
just using conditioner on our hair without shampoo is like us going to take a shower but skipping the soap and just rinsing. who would want that?
hope i helped! :)