Due to the PCV system on all my vehicles, i regularly clean all the throttle bodies with CRC throttle-body cleaner. I can clean them a couple times a year and i still get the paper towel covered in black carbony stuff each time. I notice an improvement in idle, and a warm fuzzy feeling.
You can clean them without removong the TB, just slide the boot off and manually open the valve to spray and wipe both sides. The CRC has a dry lube it leaves behind to lube the pivot surfaces.