Banned Sock Identification Kit

Step 1: Hold the sock up to the light. Is the light reflecting off a suspiciously large stain? Urine Analysis

Step 2: Smell the sock. Does it smell like a combination of mildew, despair, and desperation? Sock Odor Profiling

Step 3: Consult the Sockzilla Sock Chart

Step 4: Perform a Sock Fiber Analysis

Sock Fiber Analysis or Sock Texturing

And finally, if all else fails, just throw it away. You're not a scientist, and you're probably not going to win The Sock Hero Award with this approach.