To distinguish between inferior sofas, you can consider the following factors:

1. Material: Examine the material used for the sofa. Inferior sofas often use thinner, lower-quality leather or fabric, which may not be as durable or comfortable as higher-end options. Check for any cracks, tears, or discoloration in the material.

2. Frame: The frame is the backbone of the sofa, so it's crucial to inspect its quality. Inferior sofas may have weak or flimsy frames made of poor-quality materials. Look for any signs of bending, warping, or rust on the frame. You can also sit on the sofa and摇晃it gently to check for stability.

3. Joints and Sewing: Pay attention to the joints and sewing of the sofa. Inferior sofas may have loose or uneven stitching, as well as joints that are not securely fastened. This can lead to premature wear and tear.

4. Springs and Cushioning: The springs and cushioning provide the comfort and support of the sofa. Inferior sofas may have weak or cheaply made springs that sag or make squeaking noises. Additionally, the cushioning may be thin or lacking in density, resulting in a less comfortable sitting experience.

5. Brand and Price: While not always indicative, the brand and price of the sofa can also be indicators of quality. Inferior sofas are often sold by unknown brands or at unusually low prices, which may reflect their inferior quality.

Remember that investing in a good-quality sofa is essential for both comfort and durability. It's worth spending a bit more to get a sofa that will last longer and provide a better seating experience. If you're unsure about the quality of a sofa, it's always a good idea to seek advice from a furniture expert or read reviews from other customers.