[header] How to tell when blue cheese is bad [title] Smell the cheese. [step] The best way to tell if your blue cheese has spoiled is to smell it. Fresh blue cheese has a strong scent, but it changes as it starts to go bad. 
Give the cheese a sniff, and if it has an ammonia-like smell, it is probably spoiled. [substeps] It's a good idea to give blue cheese a smell when you've just brought it home.