I'm probably going to have to learn this kind of stuff aren't I?

Damn! I've got people coming over to the house and have a question for anyone out there reading this. Does blue cheese ever go bad? And if so, how the hell can you tell? I'm making a spinach salad with blue cheese crumbles, but I just realized the container has been in the fridge for a questionably long time. Am I going to poison anyone (like possibly my husband who is now the SOLE breadwinner in our family)? Help!!!