It won't do any good now, but FWIW, if I have to remove valve covers, I spray clean the motor (with Simple Green) and a handheld Quart or so pump sprayer on a COOL engine, rinse it with water in a garden sprayer, then run the engine until it's warm and dry, shut down again and blow the top off with Compressed air.
Much less to worry about dirt, grease, oil, dead bugs, etc., getting inside the valve covers if the OUTSIDE is already clean enough to eat off of before opening them. I would hope that all this sounds simply like common sense, which applies in your own garage, but not anyplace paid to do the work because they don't have time to care; besides, you'll never see the chunks they drop in YOUR engine.
I'm also BITOG OCD enough to always drain REALLY hot oil, after the engine is completely warm, and I use leather gloves over rubber gloves, long sleeves and have rags handy. Never been burned, I just sleep better draining my oil HOT, so I know whatever is suspended in the oil is still suspended when it's drained.