Grasp the Nettle

Lots of people
1) do things in computer role-playing games they wouldn’t actually do, for moral reasons (example: murdering a village full of innocents with magical fire)
2) do things in sexual fantasies they wouldn’t actually do, for moral reasons (example: asserting control over another human being through physical violence)
3) imagine things in their daily lives they wouldn’t actually do (example: punching a cashier in the face for being obnoxious)

Some of these might actually be morally problematic, depending on the reason why they seem interesting.

Murdering a village full of innocents in an RPG might make getting money for better armor easier. If done for this utilitarian purpose, it seems fine, as the villagers aren’t actually people.
However, if it is done for the “thrill” of hurting things which seem similar to people, it is bad. It is not bad because it makes you more likely to commit murderous acts, necessarily (a silly inference often made by mainstream TV reporting on video games), but because it encourages a theory that says being a terrifying badass with the capacity to hurt people is a good/fun thing, which has implications for other areas.

Analogous might be dealing with insects. If you kill an insect for the utilitarian reason of its annoyance, there’s not an issue — insects are annoying and have no moral status. However, if you kill it and enjoy it because you enjoy imagining it as a sort of anthropomorphized creature upon whom you are inflicting great suffering … well, that’s pretty fucked up. (Additionally, there’s the possibility of testing out theories that are not strictly utilitarian nor bad that would be ok — like dissection)

Similarly, with sex stuff, there are similar issues raised. People should want to engage in sex with people who are confident, self-assured, assertive, thoughtful, calm, and happy, because that is the natural disposition of a healthy, productive human being. If you want to be a plaything, or have a plaything, there is some theory in your mind which deserves further investigation. These theories are not consequence-free, and can often cause you to act in non-autonomy-respecting or non-assertive ways (depending on which side you fall on) in other areas of your life, or at least make it seem like a good idea to do that. You’re encouraging a theory / developing a habit of mind which associates being dominant or submissive with extreme happiness and pleasure. It’s unsurprising that this might prove problematic.

While people shouldn’t repress their sexual desires (conservative/traditional morality is bad in this sense), neither should they treat all desires as equivalent morally (modern/progressive/liberal morality is bad in this sense). If one has certain desires, like being in a dominant role relative to other human beings, then one should question why this is the case, for the reasons discussed above. Sometimes, engaging in the sex act itself (or in the playing of an RPG in order to test out theories about hurting NPC villagers, as in the above example) can be useful in figuring out what is appealing about something — the reasons why things are appealing are difficult to figure out, and direct emotional experience can be one helpful avenue. But one has to actually subject one’s theories to criticism, and not fall into the pitfall of avoiding criticism due to the irrational fear that one is fundamentally “bad” because one’s values, sexual or otherwise, may have some problems.

The last example is likely the most common. Most have experienced imaginary rage-violence at some perceived slight of social niceness. And again, the overwhelming majority will never actually engage in violence as a result of such fantasy. But what they will do is encourage the theory, which is itself giving rise to the fantasy in the first place and can be further entrenched by emotional reinforcement and repetition, that imaginary rage-induced-violence is a useful coping device for stress. This is fundamentally flawed — one should care less about social slights, and develop better theories for dealing with emotions.