Attending a sports camp would help for you to determine whether you want to play that sport at that college. I went to USNA's lacrosse camp and was able to interact with players and learn how they felt about the Academy, and hear what their lives were like. I found a lot out about the program and the coaching style just from four/five days. Assuming we're talking about a D1 sport, if the coaches are already looking at you as a possible recruit, they can use the camp to evaluate you over a wider span of time than they might normally do just from watching you play a couple games or so during a tournament. Or, if you were previously unknown to them/haven't contacted them before, you can work hard and maybe spark their interest.