https://www.vice.com/en_us/article/wxdzb5/more-than-80-of-nfts-created-for-free-on-opensea-are-fraud-or-spam-company-says

As the NFT market has exploded, so has the amount of theft and fraud associated with it. Artists are by now familiar with the experience of finding, like in a horror movie, their own art staring back at them in OpenSea's digital gallery, being hawked by an anonymous stranger. 

Now, OpenSea has revealed just how much of the NFT activity on its platform is defined by fakery and theft, and it's a lot. In fact, according to the company, nearly all of the NFTs created for free on its platform are either spam or plagiarized.