I'm a little different on this one. My LFS guy showed me that you should rinse it out. Put it in a bowl and work your fingers through it and get it all mixed up then dump that top water out (that will get out the "junk" if any). Don't worry about it not being live as you can re-seed it. My LFS told me to stop by his shop (and I found you can do this at many locations) and ask for a couple of handfuls of their tank sand from a few of their tanks. This gets all the worms, stars, etc that make sand live. Dump that "barf" (trust me it looks just like vomit) and put it straight in your tank, water and all. all that stuff will fall on top of your "old sand" and you will instantly see all the worms and critters and you will get to watch them dive down into your bed.
Thus you now have a freshly seeded live sand bed! I was told by a several aquarists before that it's best to have a good network of saltwater buddies who you know real well who take good care of their tanks and every 6 months or so, trade off - you get 4-5 handfuls of their substrate and you give them some of yours. Every tank grows different things so it is refreshing to get your bed mixed in with other critters who will get eated, die off, etc from your star fish and crabs and such.
Just my opinion of course. Others might freak with what I just said, but from a personal note and from people 30+ years in the saltwater game I found it was VERY good in my tank and I think that as long as it's good critters, the more critters the better for a universal marine world in my tank and thus they grow in and on my live rock too!