A good air freshener should be effective in eliminating unwanted odors, long-lasting, safe, and pleasant to smell. Here are some qualities to look for in a good air freshener:

1. Effectiveness: The air freshener should be able to effectively eliminate unwanted odors and leave the air smelling fresh and clean.

2. Long-lasting: A good air freshener should be able to provide long-lasting freshness so that you don't have to keep reapplying it throughout the day.

3. Safety: The air freshener should be safe for you, your family, and pets. Look for air fresheners that don't contain harmful chemicals or emit volatile organic compounds (VOCs) that can be harmful to your health.

4. Pleasant scent: A good air freshener should have a pleasant scent that is not overpowering or too strong. Choose a scent that you find appealing and that suits the purpose of the room or area where it will be used.

5. Easy to use: The air freshener should be easy to use, whether it's a spray, plug-in, or other type of device. It should also be easy to store and transport if needed.

6. Compatibility: The air freshener should be compatible with the room or space you plan to use it in, such as a small room, a car, or a large living area.

By considering these qualities, you can choose an air freshener that is effective, safe, and pleasant to use, providing a fresh and clean scent to your surroundings.