She must own stock in a thread company. Sometimes I put the spool or cone in the frig for a while before I use it but if it doesn't fall apart a the slightest tug, I use it.

This is what I was thinking. How could thread possibly go bad in a years time when we have quilts that are decades old that are still being held together by thread?

Some of my thread is 10 yrs. old or more and still strong and usable. I think that teacher was just trying to make some money for the store!

I agree that thread lasts a long time. If not, then all the clothes we wear that are over a year old would have fallen apart at the seams by now. I have a 70-year old quilt, the fabrics have frayed, but the threads at the seams and borders were still intact.
Nah, she's trying to drum up business for the LQS. She could be a tightwad and would probably pick up all the threads thrown away for her own use (jmho).

what paperprincess said is true and just don't store it where the sun shines on it I have taken a lot of quilt shop classes and never heard that before

I believe she is just trying to get you to buy something. No need for new thread. Use what you have.

I agree. I buy my thread on the cones 5000 + yards. I do not throw them out, some I have had for at least 10 years and they are still strong.

I have some very old thread (60 years, maybe?) that my MIL used for mending. If it's still tightly wrapped on a spool, what's going to cause it to go bad? It isn't exposed to the outside air. If I use it, I discard the first few wraps, but it seems as strong as anything else I have.

Toss away perfectly good thread? I don't think so. I agree with Paper Princess: check older threads by trying to stretch & break them. If it breaks easily, discard it, otherwise, it's good to go.

I hope this isn't true because I have thread that belonged to my Mother that I'm using and she's been gone for 23 years. I always test the thread before I use it, but I don't throw anything away unless it's bad.