(Or in the case of bypass shears, the other half of the tool!) Pause occasionally as you sharpen, and carefully feel the back side of the edge. You'll be able to feel (or even see) the burr forming.
Buying and maintaining a good set of tools can be expensive for the home gamer, so [shopbuilt] put together an Instructable on how to sharpen your woodworking tools on a budget. The trick is to ...