Definitely not. These types of stories usually lack any real literary merit. They are more about titillating the reader with sexual details rather than providing any kind of profound insight. Good literature should be about exploring the human condition, society, and culture, not just about sexual fantasies. And such stories can also be offensive to many people, so they have no place in proper modern literature.
I'm not sure who this 'Douglas Smith' specifically is in relation to such inappropriate stories. There could be many people named Douglas Smith, and it's not ethical to promote or be associated with 'sex smut' content.
No, it's not common at all. Blackmail in any form, especially related to such personal and inappropriate matters, is unethical and illegal. Most people respect others' privacy and dignity.
There are many great literature works that are suitable for all ages, such as 'Pride and Prejudice', which can offer much more valuable reading experience.
No. Sharing such stories is inappropriate and often violates moral and ethical standards. It may also be against the law in many places as it involves vulgar and inappropriate content.
It depends on various factors. In a committed relationship, if it's something that is privately and consensually part of the couple's understanding, it might be okay. But if it starts to affect the relationship negatively, like causing a lack of real intimacy or making the partner uncomfortable, then it's not appropriate.