booolkaakaa!

Not necessarily a reason to get new pads. Brake dust is a natural by product of using disc brakes and dirt will naturally find its way onto the system as it is an open system. You only need new pads if you got grease/oil/other lube on the current pads or they are worn to the point of needing replacement. Agree with the recommendation of cleaning rotors with alcohol.

The black stuff is most likely caused by the dust created as the pads wear down + other dirt mixing in with it. If your brakes feel solid and are providing you enough stopping power then just clean the rotors and leave everything alone until you NEED to replace the pads. If you feel the need to clean things up then use a rag dampened with water or alcohol to clean things up around the brakes...better yet lookup the instructions on how to remove your pads and remove them before cleaning the area, then replace after wiping everything down with a damp rag. Clean as often as you feel necessary. But don't sweat it too much, just get out and ride.

-j