It isn't logic, it's naivete. Some baits are manufactured with inconsistencies that aren't apparent looking at them - they *seem* identical. If you are used to working a bait a certain way, when you replace with another bait that has these variances, it acts differently, and isn't doing what your old bait did, which happened to be what fish consistently bit. That's what we're talking about. There's no way to tell if they're identical without fishing them. When you lose that bait that was working, you probably want to replace it with another, but you can't assume that it will work as well just because it is superficially identical. Some baits are terrible. I provided an example, and a few others provided more. This is why I prefer to use certain brands that have built trust in the quality and consistency of their baits. They also happen to usually be a a little more money, but you get what you pay for.