Never put straight degreaser on your cam covers, it stains them and they look crap until you have them polished or painted, if you have to degrease, water it down.
Also - Wait for the engine to cool before you spray it with cold water or you risk cracking the exhaust manifold or worse - the head.
Cover your pod filter (if you have one) with a plastic bag, everything else should be fine as long as you dilute the degreaser.