Pansexual & polysexual
These are very similar, and are fairly unnecessary considering that bisexual already exists (and covers all available options).
Some arguments against pansexuality as a term:
- By moving transgender/transsexual individuals into the pansexual spectrum, that is morally wrong. Pansexuality is a transphobic/cissexist term in their defining sexuality by “being attracted to men, women, and trans” (it implies that trans persons are not men/women) and it is biphobic/bi-erasure by imposing the definition of “an individual who prefers cisgendered female or male partners” on Bisexuals who do not want or need that definition. Bisexuals already have their own communal definition which suits them just fine.
- The American Psychological Association does not recognize pansexuality or polysexuality (which doesn't fit on the Kinsey Scale) and instead, they use bisexual.
- Reading a bunch of stuff here will help explain things more. Bisexuality is the most commonly accepted term in academia and it’s inclusive for all genders.
- "Though the definition of pansexuality encourages the belief that it is the only category that covers individuals who do not cleanly fit into the categories of male/female, the term bisexuality includes attraction to intersexed and transgender people (who may identify as men, women, both or neither)." (via Paula Rust and Michele Amestoy)
Pan/poly are also subcategories of bi (preferences) and technically not stand-alone labels as some people claim. Their only usefulness is to be extra-specific about one's romantic or sexual attraction(s).
- Bisexual = you have the ability to be attracted to multiple sexes/genders.
- Pansexual = you have the ability to be attracted to multiple (any/all) sexes/genders
- Polysexual = you have the ability to be attracted to multiple (not all) sexes/genders
Demisexual
"Demisexuality" was created by a 15 year old girl as a mock orientation on a roleplay forum. As a result, the term doesn't hold much credibility. However, people have latched onto it and think it's real; some have created elaborate explanations to justify the usage of "demisexuality" as an actual term.
The typical explanation people use is derived from a bastardized version of Rabger's Model (which itself was based off unscientific ponderings on a forum as to how sexuality might work), something which introduces the concept of primary and secondary sexual attraction. However, many people do not agree with how this works or defines things, especially with the person who came up with the original ideas (Rabger) decrying this as inaccurate and not at all what was originally envisioned. The debate around this still exists and is something primarily discussed exclusively within the online asexual community. Most academic theories of attraction are related to scales of human sexuality, something demisexuality is highly unlikely to fall on.
But let's pretend for a moment that all of the above is irrelevant. Demisexuality still wouldn't be a thing; demiromantic would be more apt. It’s “I don’t have sex with anyone unless I know them,” which is a way of expressing sexuality, not a sexuality in itself. Demisexuality is not deserving of a “-sexuality” label, since it doesn’t imply anything about attraction to gender/sex like every proven and accepted sexuality does (heterosexual, homosexual, bisexual, asexual).
Even if demisexuality was an actual orientation it would be redundant, as its aspects fall under the grey-Asexual label. The definition of demisexual doesn’t cover anything that isn’t already covered by the definition of grey-a, since it is a subcategory of grey-asexuality. From the asexuality wiki: “The term demisexual comes from the orientation being ‘halfway between’ sexual and asexual.” This is exactly what grey asexuality is - being into the “grey area” between sexual and asexual. All demisexuals are grey-asexuals, as they're primarily asexual but can experience certain kinds of attraction under certain circumstances.
Therefore, given all of the above, “demisexuality” as a term is useless. Logically it makes more sense to use other terms than demisexuality. If you want to use the term, okay sure, but it doesn’t make any sense to do so when there are far better terms out there that cause less confusion.