First, the way a person dresses and accessorizes can be a strong indicator of their subcultural affiliation. For example, someone who wears black clothing, band t-shirts, and combat boots might be perceived as emo, while someone who wears bright colors, neon accessories, and tutus might be perceived as scene.
Second, the music a person listens to can also be a strong indicator of their subcultural affiliation. Techno screamo is a genre of music that is often associated with the scene subculture, while emo music is often associated with the emo subculture.
Finally, a person's values and beliefs can also be a strong indicator of their subcultural affiliation. For example, someone who values individuality and self-expression might be more likely to identify with the scene subculture, while someone who values conformity and belonging might be more likely to identify with the emo subculture.
In addition to these general factors, there are a number of other things that can influence a person's perception of another person's subcultural affiliation, such as their age, gender, and geographical location. Ultimately, it is up to the individual to decide what subculture they identify with.