Crud likes to build up around the atomizer especially after a automated cleaning process. Regular washing should stop this from happening so much. I use warm water in a ultrasonic cleaner I got off of amazon for 30 bucks. I've had my generic 4072's for weeks now they both work like champs and I've been regularly cleaning them. I let one go for a little too long (after the automated cleaning process) without an ultrasonic cleaning and it made black specs but not so extreme as the pictures here. after a cleaning the bad taste goes away and the black specs stopped. Maintenance is the key, tweezers are your friend.
Whats your cleaning cycle like? I like to blow mine out with some paper inside of it and then put it in the ultrasonic for 3 minutes in warm water. I try to do this often, once every few days. Really helps these generics last last last.
Also, cleaning them right out of the box helps. Factories are dirty places don't take any chances.
Just my 2 cents, hope this helps.