Plug choices can be overwhelming. Even after you do all the research for what is the best colors and sizes, it still is a bit of a lottery. Any serious plug fisherman has stories about seemly identical plugs where one catches fish, and the other doesn’t.
Unfortunately there is no way to tell at purchase time if that plug is going to be a winner or not.
But as you fish the plugs, the winners then start self identifying. They will accumulate bite marks on them.
Other plugs never seem to catch fish. For those plugs – once you feel that you’ve given them enough chances – it is best to move on. Throw them away and replace them with new plugs that might be fish catchers.