When cleaning LCD panels, including laptop displays, be very careful.  The plastic coating on the front of the display is semi porous, so fluid can run down the front of the display and short out some of the edge transistors, blowing out some of the display elements.  Pre-moistened towelettes are the best way to go, but if you prefer a spray on cleaner, use it very sparingly.

If, however you use a CRT (old style) then you can use sprays, however, it is advisable to clean it when your monitor is off.

It is advisable to keep your monitor clean as this may help prevent eye stratin. It also means you don't see full stops when writing letters which you can't delete (dirt on the screen).