Once you fill out the recruiting questionaires it leads to more mail, most likely invites to camp programs. While many programs find possible recruits at their camps, do know that the purpose is to raise money.
If this is a school your son is interested in, you might possibly consider. I would inquire about the camp, not all camps are created equal. Just heard recently of a well known school having a poor camp (coach was barely seen at all). And if a head coach attaches his name to the camp, I would expect he should be their to run the camp. If not, possibly it may just be run by assistants and or scouts.
If a school is really interested in a player, not attending their camp will not make a difference.