Yes, it do...
Hi, James. Yes, mono does go bad. Some products have UV inhibitors, others, usually clear, don’t. Maxima Clear has no UV protection. If you keep mono in the dark and in the fridge (no, not kidding) it can last decades. I have an Orvis mono leader tying kit from the early ‘80s, stored in the fridge, still testing as if new. And my newest leader spool, 15 lb Maxima Ultragreen has turned out to be rotten – connected a length to 10 lb Orvis via perfection loops and pulled ‘til failure, the Maxima broke. I think the fluorescent lighting in the tackle shops has a deleterious effect on all mono. Like Ard said, test your stuff, even new stuff. Cheers, Buff.