Leave it open-ended and include code with multiple levels of bad so it's not just a quiz. I used real C code that research scientists had given me. If they look at it and say there's no reason this should be in C and in a dynlang instead, that is fine. If I hand them C code where the entire program is a 1000-line main function, with lots of repetition, hard coded file names, and fixed-sized string buffers, and all they tell me is the indentation is icky: that's a negative signal.