Generally speaking .. the carnivorous stars have raised bumps, e.g., chocolate chip star. And those .. well .. they're probably easy to feed prepared foods. But there may be incompatibility issues, so probably they don't really get an overall "reef safe" approval rating.
The smooth stars, such as linckia's, are not well understood (at least ... what they eat is anyone's guess) and their success in captivity is hit and miss. There are very scattered reports of them taking food, but most of the time they will not take to prepared foods. Basically your best bet is to have a large biodiversity in your tank (large system, lots of live rock, etc.), and hope that there's enough of whatever slime they eat, happening in your tank. They'll pose little threat to livestock in a reef, thus, they could be considered "reef safe" but whether they do well themselves over a long period of time, is the question.
Rob Toonen has written a number of articles about stars ... you may find more info in one of his articles.
Here's a link to one in advancedaquarist.com ->
http://www.advancedaquarist.com/issu...002/toonen.htm
There is also a back issue of reefkeeping.com which talks about stars, I'm not sure it's by Rob though. Unfortunately due to Jeanne or whatever hurricane it is today, RC's servers are down so I'm not able to find the specific link for you at the moment. When their servers are back up you may want to try a back issues search to see what hits you get.