Hey Samantha, your post and the comment that "anonymous" left about fire hazards reminded me of the state our dryer was in when R took it apart recently. Our dryer is 12 years old and hadn't been drying very efficiently for ages. It needed a part fixing around the door and when R went to replace the thing we found it had years of lint buildup inside, which of course is a hell of a fire hazard! We also ended up replacing the belt that turns the drum AND the heating element at the back. There weren't any socks in there though ;o)
My dryer now works much better and I definitely think these machines should come with a recommendation to vacuum them out every year for safety reasons.