Plenty of shady characters, and in many cases, people (or objects) aren't really as they seem. Characters -- many of whom are kids -- often break rules in response to the danger they're put in, but things usually turn out for the best in the end.
Content varies greatly from one story to the next, but on the whole, violence seems to take a backseat to the fright factor. What violence does exist is limited to threats with household weapons like knives. However, the show's spook factor is a concern for kids. Inanimate objects move on their own and often have menacing motives toward the people around them.