The short answer is no—not automatically. A plastic liner doesn’t create smell by itself. What it changes is the little environment inside the trash can: airflow, moisture, and how much gunk sticks to the bin.
In some cases, a lined urban trash can really can smell worse. If the liner traps condensation, keeps food scraps and liquids sitting at the bottom, and gets changed only every few days, it can create a sealed, sour-smelling pocket. If the bag tears, leachate pools in the bottom of the can, and the liner blocks airflow, the smell can get rough fast. A liner can also hide mess from workers, so the can may get washed less often than it should.
But an unlined can is not automatically better. Without a liner, wet waste can soak into scratches and seams, food can stick to the walls, and liquids can seep into the bottom. That residue can keep smelling even after the trash is emptied. On a hot day, an unlined can with old food waste and no regular washing can be just as bad—sometimes worse.
So the liner itself is not the villain. The real difference usually comes down to how often the can is emptied, how often it is cleaned, how hot it is, what kind of waste goes in, and whether liquids are controlled. A lined can that is changed often and washed regularly can actually smell better because the liner contains the mess. An unlined can that is rinsed and dried often can also be fine, because it has better airflow.
The worst-smelling urban trash cans are usually the ones with poor maintenance—not simply the ones with plastic liners.