This happens with cutters made without specific knowledge of 3D tool design or moldable materials. A properly designed cutter has sharp edges that leave no residue or only a minimal one. These are delicate tools and require proper care. If you choose low-quality cutters, your post-processing work (sanding and polishing) will be much greater, and in some cases, even after sanding, you may still end up with uneven and unprofessional edges. Choose high-quality cutters that will last longer and deliver better results.