Meanings of perpetual snarl in English

I approached the podium, and the prosecutor, a towering figure with wavy hair and a perpetual snarl, began grilling me.

It was a comfort to be able, for once, to enjoy themselves without fear of Mrs. Colwyn's perpetual snarl and grumble.

Her black lips were drawn back over her full set of vicious, gleaming white teeth and fangs, as if in a perpetual snarl.

Billee's one fault was his excessive good nature, while Joe was the very opposite, sour and introspective, with a perpetual snarl and a malignant eye.