What would be the reason someone doesn't get hit on?

-not physically attractive to observer
-bad/irritating attitude (again, to observer)
-uninviting body language (arms crossed, crunched over, etc.)
-resting bitch face
-known tendency to read to far into things that aren't meant to matter

Looking unapproachable

Not wanting to spread communism. A big turn off for me.

Their inner circle is a curse not a blessing.

They don't look friendly.

They scary as hell

In your case it's probably because you're too shy and don't look approachable. Not trying to hurt your feelings, but that's the impression that you give here.

Lack of confidence. We can sense it even unconsciously.

Being ugly ,no personality ,they don't have a body that society says is sexy ,so many reasons

They have seen my selfies

They look scary. That is the look I go with.

Head stuck in a phone

Invisibility

age

Lots. Sometimes, a person is terrified of rejection.

They smell bad.