A healthy air plant has firm, pliable leaves and doesn't have any yellowing or brown leaves. It should also appear bushy and evenly filled out, with leaves spaced fairly evenly. Avoid air plants that are dry along the edges or make a crunchy sound when squeezed. A healthy air plant should have a vibrant green color and look lively overall. It is important to choose a healthy air plant to ensure its longevity and thriving in your space. Remember to provide the proper care and environment for your air plant to keep it healthy and happy.