In that case, you could try a mixture of mayonnaise and water on a soft cloth. That's what I used to clean the leaves of my orchids and make them shiny. I was told this is what people who show their orchids use.
The mayo has a little vinegar and a lot of oil, and you cut it with water just so it is thin enough to leave a sheen but not a greasy residue. It took off a good deal of the hard water deposits I had on a few orchids I had adopted from a fellow who watered them with well water.
