The form of Bhairava is considered to be fierce and terrific, one that infuses more fear than love towards Lord Shiva. Bhairava is known to be a naked mendicant or at least follows the same iconographic appearance as Bhikshatana where he is depicted ash clad and naked.
As described in the Shivabhaktavilasam, Dabhra Bhakta, an ardent devotee of Lord Shiva was being tested for his devotion to the Lord. In order to show Parvati the intensity of Dabhra Bhakta's devotion, Lord Shiva descended to the earth in the form of Bhairava to his residence. Dabhra Bhakta, unaware that the very Lord had descended, was blessed to have seen this form of the Lord and as he directed the stranger who had come begging for a meal. As he guided his guest back home, he describes his appearance as follows:
He appeared to be a staunch Maheshwar, with the very grace of Lord Shiva shining upon him, a stranger who had come to this little town, and had knocked at his door asking for a meal. As Dabhra Bhakta was not at home, the mendicant went to the nearby Ganapateshwara temple and waited. On hearing about his arrival, Dabhra Bhakta rushed to the temple to invite the mendicant home. As he neared the temple he saw an aged man sitting under a tree and meditating. His left elbow was supported by a Yogadanda his staff, and he had a Brahma Kapala (skull cap that serves as a begging bowl) near his right hand which was engaged in counting the beads of his rudraksha rosary as he chanted within his mind. His effulgence beat the very beams of sunlight that lit up the day. He looked aged and yet very rugged. He was ash clad and in deep meditation when the invitation for a meal was brought over to him.
He rose up from his seat in all his majesty and grandeur. He took out a handful of ash from the pouch in front of him and smeared it all over himself, forming a little cloud of holy ash that almost crowned his brow like a halo. He help the kapalam and skull bowl in one hand and played the damaru in the other hand creating a sound so loud and terrific that it echoed his arrival through the little town. He wore a waist band of skulls which rubbed against each other as he walked on gracefully. His thick silver tresses were neatly held up tightly in his elaborate jatamukuta which he tied with a garland of smaller skulls. He was smeared with red gorochana on his forehead and it seemed like the fiery third eye spread fear over his brow while his eyes showed great compassion to the world. And as he walked, his over sized anklets tinkled on manifesting the primeval nada - the cosmic vibration.
That was Bhairava then, depicted in scriptures and sung about and probably He walked this very earth in the previous yugas. A depiction so clear that it became the definition of "Shivahood" among the yogis of the coming centuries. The yogi attire has not changed much since then, though with a few alterations to the described visual appeal. But none have come even close to matching the Lord's form, His beauty, his very presence that reflects in the eyes of the aspirant, one who has immersed himself completely into the worship and love for the Lord, living in a real trance as he journeys into His adoration.
These are the possible appearances of Bhairava today, those that somewhere remotely match the Lord's original splendor but seem to have lost the essence of His presence in their eyes!