Short answer: yes, they can help quite a lot, but they are not magic. An enclosed top mainly does one simple thing well: it limits airflow between the waste inside and the air around it. That means smells stay more contained instead of drifting out all day. It also keeps rain out, which matters more than people think—wet trash breaks down faster and creates that sour, swampy smell. A good enclosed lid can also keep flies, birds, and stray animals from getting into the bin, and that alone makes a public area feel cleaner.
But “reduce odors” is not the same as “eliminate odors.” If the bin is full, the waste is sitting in summer heat, or the lid seal is loose, the smell will still build up inside. Then when someone opens the lid, it can hit you in the face all at once. I’ve seen enclosed bins that smelled worse than open ones simply because they were emptied too rarely and never washed. The enclosure traps the smell, but it also traps moisture and bacteria if the bin is not maintained.
So in real life, enclosed-top bins work best when three things are true: the lid fits tightly, the bin is emptied often enough, and it gets cleaned regularly. A pedal-operated lid or a self-closing flap helps because people do not have to touch it and it closes right away. In busy public spaces, I’d say enclosed tops are worth it—they cut down the constant background odor, keep rainwater and pests out, and make the area look tidier. Just don’t expect them to fix poor waste collection. They reduce odors noticeably, but only as part of a decent maintenance routine.