Verified answer

As long as they are kept in an airtight container they will last almost indefinately.

Do Sugar Cubes Go Bad

If they get too humid they will get real rock hard. You will be unable to crush em or even worse they will crystallize up. A bigger problem is improper storage and absorption of odors.

If they are kept in say the same cupboard as garlic you can get some rather interesting off tastes.

How to tell. Too moist like a said won't crush down, Off flavors will taste well.. off

JSin

They can go bad, but that's if you have them out on your counter not covered. In 4-6 months they will turn a yellow color.. but they will still be fine to use.

Sugar doesn't go bad like other foods. You should be fine.

yes they will harden and turn yellow