I do clean my orchid leaves with a mixture of mayonnaise and water. This has oil in it and does make the leaves shine and also the vinegar in it removes any hard water deposits from the leaves (which really do clog the stomata up). But I also wash the oily residue off the plant after a few hours, and never leave oil on any leaves that may be in the sun. The leaves can burn. People who show their plants do use things like mayonnaise or oil/water to make their plants look nice, but I'm sure they wash it off after the show, too.
A very mild solution of dish soap, sprayed on your plants top and bottom, then rinsed off with plain water will get rid of the oil residue. The amount is no more than 1/2tsp. of dish soap to a quart of water. More is not better when it comes to soap, as it is salty and very alkaline.
The soapy water spray is also what I use to control insect problems if I have any. Again spray all parts of the plant, and rinse off with water.
