How much black stuff should be on my MTB's derailleur/cassette/drivetrain if any?

First off, I bought this bike used, and have only ridden it twice. After the first two rides, I hosed it down and used a washcloth on the larger components (frame, rotors, seat post, rims, etc.) then I lubed the chain. I plan to take a brush to the cassette, derailleurs, and chainrings as well as use a Park Tool chain-cleaning kit on the chain after my third ride. But anyhow, I noticed that there is quite a bit of black build-up on the cassette, teeth of the chainrings, derailleur pulleys, as well as the chain itself. Not an insane amount, but more of like a medium-thin coating. Nothing is too "gunked up" or anything, and you can still see the most of the metal through it, but it sure isn't shiny. The cassette has the stuff on it, not completely black and thick, but again, it just is not shiny. The chain has enough on it for a decent amount to rub off on your hand if you brush against it. The derailleur pulleys probably have the most "gunk" on them. Should I have this much, or am I overdoing the lube? I use Rock 'N' Roll Extreme if that makes a difference. Also, anything more cleaning I should be doing? Any tips? This is a pretty high-end bike, and I'd just like to keep it as clean as possible. Thanks.