How can you tell if Blue or Gorganzola cheese is turning bad?

Cut away the bad parts and see if it still seems fresh on the inside - if so, just cut away the undesirable sections. If the interior seems suspicious, it's time to toss it. In addition to wrapping it in waxed paper or foil - I often see it first wrapped in wax and then foil - use it more quickly next time!

All cheese keeps better wrapped in waxed paper than in plastic wrap.I've found if you keep cheese in waxed paper, it may dry out a bit but it won't spoil.

Blue cheeses tend to be soft cheeses, and these are better kept in aluminum foil. I'm not sure why, but all the cheese mongers do/say that.

I agree with hardlikearmour. Of course both cheeses depend on mold to be themselves but the white should be fresh and white and definitely not slimey. Once a cheese is cut open it begins to degrade. Think of it as a still living organism that you've just stabbed to death. And cheese rind rules.

The texture and color will change. It will typically get slimy to some degree. You may notice grey, tan, or pink areas. It will taste bad.