Being bicurious is not typically a sexual orientation like bisexuality. You can consider bicurious people as those who travel from one end of heterosexuality to the other end of bisexuality. Unlike bisexuals, it is very complicated to identify a bicurious person, and it is also hard to keep that person under one roof. Simply, any person may get confused while trying to label a bicurious person. They may be straight or maybe bisexual and this confusing state continues forever if you don't know how to identify them. Hence, a few signs may make your task easy to understand, comprehend and perceive a bicurious person.
For starters, it is always better to consider a bicurious person as a heterosexual who is interested in exploring a hidden side of his/her bisexuality. The exploration could be completely physical and sometimes emotional. Most bicurious people try to explore sexually to know whether they can feel the vibe of a fellow same-sex person. Bi-curiosity is all about curiousness and most of the time, it stops at just being curious instead of being experimental. So, altogether, never expect a bicurious person as bisexual.
We, humans, work on signs only when we get confused in recognizing a particular person or a situation. If someone who tags himself/herself as heterosexual, approaches you repeatedly even though that person knows you belong to the queer community then you need to make sure whether that person is interested in you or just being curious to know you inside out. Hence, you need to eliminate the unnecessary choices to get partial clarity.
Homophobic or queerphobic folks can never be bicurious. They are judgmental about the whole queer community and they keep expressing their suppressing views. But some people pretend to be homophobic just to satisfy typical societal norms. Mostly a homophobic person can never express curiosity towards same-sex encounters. But if a person supports you privately and expresses his slur on queer people in public, he could be curious towards you but it's better not to entertain such double standards people. So, you need to eliminate this choice for sure.
Next comes, the queer allies. These sweet heterosexuals bring true power to the queer community by giving their immense support and by lending their shoulders to queer people to lean on. They never judge, and they are quite flexible in exploring their sexual fluidity. So, there are high chances for queer allies to become curious to know how a queer orientation works in society be it homosexuality, bisexuality, transsexuality, or asexuality. If a known queer ally of yours approaches you with an underlying intention of knowing you completely and getting along with you in every possible way, then yeah get ready to deal with a bicurious queer ally.
Always remember the fine line difference between romanticism and eroticism. A bicurious person may have romantic feelings towards a same-sex person but he/she may not be comfortable thinking about having sex with a same-sex person and that's completely fine and that's how bi-curiosity works. So, instead of reading between the lines, just read the way it is. There is no mandatory in taking the curiosity to an extreme of implementation. This also helps you as a queer person to lessen your expectations and not to get emotionally disturbed and disappointed.
A few heterosexuals have fantasies of being with homosexuals to explore their sexual tendencies towards same-sex people. A heterosexual can have sex with a queer person and can still tag himself/herself as straight and of course as a bicurious person. These people take the curiosity to another level in which they truly explore and leave it clearly with no more intentions of completely getting inclined towards same-sex people or swinging between both genders. Generally, queer people strike off such heterosexuals as merely hidden bisexuals but practically they aren't. Because bisexuality isn't a fantasy. It is a true orientation where a person gets truly attracted to both males and females. It's never a fetish and could never happen under intoxication.
If a straight person approach with a clear agenda of having sex with you as a one-night stand or for a few hookups and tags himself/herself particularly as bicurious in exploring sexual fantasies, then yes, that's a clear sign of labeling a person as bicurious even though that person has sex with you. Erotica helps a person to ease with curiosity. Until and unless that person expresses his romantic feelings towards you, he remains a bicurious person.
And then comes, the typical bicurious crowd with too many questions, too much curiosity, and an endless confusion state. If a straight person constantly asks you regarding your queer lifestyle, your dating scenario and even shows interest in your sex life and who repeatedly throws you tons of hints that specify some kind of romantic interest towards you even after being aware of your orientation and lifestyle, then yes, that one is a bicurious person.
Some straight people struggle with blended feelings towards same-sex couples and other straight people. With a lack of knowledge or exposure, these straight people crush their curiosity for the sake of society and try to never open up even though they feel like trying to explore their inclination towards bisexuality. If you are a queer person who encounters such straight people, you need to educate them regarding various orientations other than heterosexuality. With proper terminology and presentation of broadening thoughts, you surely witness the aspect of vulnerability in such a bicurious crowd. They can be curious forever and some of them may truly come out as bisexual after a few queer encounters.
Regardless of sexual encounters with queer people, a straight person remains a bicurious person until and unless his/her romantic, personal, and psychological attractions swing both ways. If it happens, that bicurious person may get inclined towards bisexuality. But it takes time for any person to get clarity on one's sexual orientation. In the case of a heterosexual person, being bicurious is the first step to exploring one's sexual fluidity, and being a queer person, you need to identify such bicurious people and maintain proper clearance to get rid of unnecessary confusions and consequences.