Q: dunno what possessed him-and yes its make my screen shiny but its dead greasy and all the dust is smeared on- will it damage my monitor in the long run and whats the best way to clean it off?
A: WD-40 is an oil based cleaner, so my suggestion would be to first try wiping away the oil with a paper towel, and then cleaning your monitor with dishwasher detergent/cleaner. Dish washing fluids usually dissolve oils, so that might do the trick. If that doesn't work then you can try alcohol or isopropyl cleaners (glasses cleaners). Oh, and unplug the computer and monitors while cleaning. It shouldn't damage the monitor as long as it doesn't seep into the circuits.