If I end up disliking a shampoo's effect on my hair and skin, I use it to wash my shower
A bit of baking soda, shampoo, and an old scrubby poof works decently and even better if the shampoo is a cheap cleansing type. That some shampoos clean the tub decently might be a cause for concern...
Otherwise if I like the smell but it doesn't play well with my scalp, sometimes it gets relegated to "cleansing cycle shampoo" or body wash.
Right now I'm using the giovanni line and while it doesn't foam up, is better for my scalp which can get dry with sulfate shampoos and traditional alcohol based conditioners.
Now to find a use for lotion I end up disliking. It's usually for the smell over the consistency, but some lotions are just hopeless on the moisturizing front.