When evaluating soap bubble guns, prioritize motor durability and leak-proof design. Ensure the product features a 360-degree leak-proof silicone seal to prevent fluid from damaging the battery compartment. For high-performance models, look for multi-hole nozzles (e.g., 10 to 64 holes) that can produce thousands of bubbles per minute. Additionally, verify the battery type; while AA batteries are common, rechargeable lithium batteries are increasingly preferred for high-end, eco-friendly market segments.