Even the best discs can scuff, puncture, tear and even crack over time and under certain conditions. Its always a good idea to give your disc a quick look prior to play. Some minor maintenance when needed can prolong the life of your disc while keeping your best buddy safe and happy.
First, and I think most important. Never use a disc with a any sort of a crack. Even if its in the middle, away from where it will be caught. Disc cracks can especially occur in cheap discs made with non pet friendly materials. However, even a better quality disc can crack over time due to age, a very strong bite and especially cold weather. Some manufacturers make discs especially for cold weather use. The Hyperflite FrostBite is a good example. So get rid of any cracked discs, its just not worth the risk to you or your dog.
In many cases, minor scuff and punctures can be filed. I've seen folks use emery boards, nail files, even a Dremel tools to take down rough edges and puncture dents. This practice works best on thicker discs of course.
The main thing is when you check the disc, anything that can injure your hand, can injure your dog's teeth and gums more.