Gustatory sweating (auriculotemporal syndrome) describes both a physiological response to hot and spicy food - facial sweating - and a pathological state, Frey's syndrome, which is a late complication of parotid surgery in about 25% of patients.

• in 1923, Frey reported this syndrome as a complication of infection of the parotid gland. As a result, gustatory sweating related to parotid surgery or injury is known as Frey's syndrome.During surgery of the parotid, parasympathetic secretomotor fibres may be divided. The fibres originally inervated the parotid gland. However, the fibres regenerate in the skin where they assume control of sweat gland activity. This inappropriate innervation results in facial sweating occuring in response to salivatory stimuli - the sweating in this situation is usually on one site of the head.
• gustatory sweating is also a rare complication of diabetes mellitus. In this case sweating may occur on both sides of the head, with mild or substantial severity. It is thought to be due to axonal regeneration within the autonomic nervous system (1)
• Botulinum toxin A injection is a safe and effective treatment with long-lasting effects for patients with extensive gustatory sweating (2)

Reference:

1. Diabet Med. 1996 Dec; 13(12): 1033-7.
2. Head Neck. 2003 Aug; 25(8): 624-8.