Distinguishing good outdoor WPC decking from bad involves several key factors:

1. **Material Quality**: Check for a high percentage of wood fibers and quality plastic. Good WPC should have a balanced ratio, providing strength and durability.

2. **Surface Texture**: A well-manufactured deck will have a consistent surface texture that mimics natural wood. Look for slip-resistant finishes.

3. **Color Consistency**: Quality WPC should have uniform color throughout. Uneven coloring may indicate poor manufacturing practices.

4. **UV Resistance**: Ensure the product is treated for UV protection to prevent fading and discoloration over time. Look for warranties that cover UV damage.

5. **Moisture Resistance**: Good WPC should have low water absorption rates, which helps prevent warping or swelling. Check for moisture resistance ratings.

6. **Warranty and Certification**: Reliable brands offer warranties that cover defects and performance. Look for certifications indicating compliance with industry standards.

7. **Customer Reviews**: Research customer feedback and ratings. Consistent positive reviews often indicate a quality product.

By evaluating these aspects, you can better determine the quality of outdoor WPC decking.