Okay, I looked through the comments and since nobody really pointed this out I specifically dredged up my Newgrounds account details just to sign in and mention it.
I enjoyed the game for like the first two rounds, then the repetition of it got to me and I started throwing out only the stuff I was meant to let through and attempting to let every single defective item go past.
This was WAY MORE ENJOYABLE than clicking on the defective items. It forced me to pay more attention and made the game more challenging. Basically what I'm saying is, if you made the goal of the game to click on all the good cans and throw them into the box, while allowing the bad stuff to fall into a bin, you would still simulate the stressful repetitive tasks suffered by a factory worker without making the player suffer the same level of boredom.