When I applied to Camp Leaders, I was expecting the best summer ever. The reality is that not only I missed different lots of other opportunities, but also money, time and tons of phone calls.
Even though I was told that about 99% percent get placed, I was one of those 1%. Personally, I think there are more that 1% in my situation each year.
I think that if someone wants to do this during summer, they should directly contact camps, as the chances of getting a job would be higher.
Moreover, if you do so, you won't have to pay ahead a big amount of money and not even have a job secured.