Smearing.

Can anybody help with regards to smearing. My 5 1/2 yr old has been doing this for some time. It started with poo (sorry can't think of a more pleasant word to jazz that up). The onsie trend seems to have resolved that at the moment. Now it's anything he can get his hands on toothpaste, shower gel, creams, nail varnish etc etc. I try to give him access to shaving foam and soap to smear in the bathroom and shower. Would aromatherapy oils help does anyone know? I can't work out if it's the smell or feel that's making him tick. I don't react when he does it just clean it up and tell him to wash his hands but I am so sick of constantly having to clean carpets and such.