RE: WD-40
I really don't like to clean my guns with WD-40, it is a magnet for dust and other trash that will form a heavy "crud" on certain parts of the gun if you don't watch it. You also need to make sure that it doesn't get on any of your shells, it will ruin them.
I like to use a can of compressed air, followed up with a little Rem Oil, the teflon based stuff doesn't seem to collect dust quite as bad.
No, I don't think spraying your gun down with anything is "really cleaning" a gun. You would need to break it down and scrub it for me to consider it "really cleaning" a gun...but spraying it down with any rust preventative is preferable to doing nothing.
Gordon