Over the years, I've found that I'm most successful with plastics that remain attractive at rest. So let's use a silt bottom as an example. If your choice of plastic is compact with short appendages, like a tube or grub, then your bait may get completely covered in the soft silt at rest, rendering it invisible to the fish. If you were to use a slightly larger bait with longer appendages, it likely won't disappear in the silt, and the tentacles protruding from the bottom may actually entice the bass. This is one reason why baits like large worms and gangly creatures work so well in swampy regions. On the flip side, in Northern regions where rocky and hard bottoms are more common, you're more likely to have success with the compact plastics that bounce off the rocks while remaining highly visible and keeping definitive bottom contact at all times.