It's scary but true. Many camp counselors -- the people responsible for watching over children for days or weeks at a time -- aren't subjected to background checks before they're hired. Think about it. Since many counselors are young, they haven't had time to establish any kind of criminal record that can be checked (remember, juvenile records are forever sealed after a person turns 18).
Camp directors have several tools at their disposal to make sure they're hiring qualified employees. Besides traditional background checks, they can use online volunteer tracking programs and call the candidates' past employers. The simple act of checking references can go a long way as well.
As for parents, ask about the background-checking process when you're choosing a camp. You can also do a little sleuthing yourself. Run the camp's employees' names through the national sex offender registry, and perform Internet searches and public record checks of any suspicious persons (like the scruffy-looking, 40-something cook or the shifty-eyed groundskeeper). Everyone will probably come up clean, but conducting research can help ease your mind!