The quality of NFTs is not guaranteed as it is a decentralized and unregulated market. However, the authenticity and ownership of NFTs are maintained through blockchain technology, which ensures that each NFT is unique and cannot be duplicated or altered. The value of an NFT is ultimately determined by market demand and the reputation of the artist or creator who produced it. As with any investment, buyers should do their research and exercise caution before purchasing NFTs to ensure they are getting a high-quality and legitimate product.