In Macbeth, how do Banquo and Macbeth describe the witches appearances when they first encounter them?

Banquo describes the witches when he first encounters them as withered and dressed wildly: "wither'd and wild in their attire." He says they don't look like earthly creatures: "they look not like th' inhabitants o th' earth." He asks if they are alive, which indicates that he thinks they may be ghosts or spirits. He then describes how they put a "choppy finger" on a "skinny" lip, as if saying sshhh to him. He says he thinks they are women, but that they have beards, so their gender is confusing. 

Macbeth describes how the witches disappear, saying they "melted/As breath into the wind." 

These descriptions indicate that the witches are not real people but supernatural forces from the spirit world. 

Later, in pondering their words, the implications of what they say "unfix" Macbeth's hair and they make his heart beat wildly. This is not a description of the witches but suggests their supernatural, unholy and frightening quality as they plant unspeakable thoughts into his mind.