Chelsea French on her 'Summer Style' card DOES seem to use milk. It does pour like a normal liquid.
As for the shows that use lotion of whatever type, I always thought it was something like sunscreen or moisturizer, seeing as how the whiteness rubs away, leaving the girls with a nice glistening!
In Marie's 'Sexy Plumber', she appears to spread dirty oil on herself. Ties in with the "grease-monkey" theme of the card.