Maybe I got it wrong but I always thought they were bad. I'm not trying to kill your sales but I think people need to research what they are putting in their tank before they pull the trigger.
http://www.nano-reef.com/invertebrates/?id=9
Class: Asteroidea
Order: Spinulosida
Asterina starfish, or more commonly known as Fiji starfish are generally dime sized or smaller with a large body, irregular arm length, and an irregular number of arms. They tend to hide among corals and in the crevices of the live rock during the day and can sometimes be seen clinging to the corners of the tank. This type of starfish has been shown to eat coralline algae and some corals; specifically acropora, xenia, green star polyps, zoanthids, and several types of soft leather corals. These starfish divide across the main body with two or three legs of varying lengths and multiply rapidly. Remove these starfish if they start to bother your corals.