Witches never use salt and avoid it at all costs. According to medieval records, you'd know you had sat down to dinner with a witch if one of your guests complained that her food was too salty and refused to eat it, or kept the salt cellar as far away from her as possible. Legend states that in Europe, all fairies hated salt, and as witches were known to cook offerings for the fairies, a witch, both in her daily life and her magickal one, would learn to studiously avoid salt of any kind.
In cultures where it is the custom for a woman to cover her head or tie her hair up neatly, a witch will always wear her hair loose and uncovered. Dirty, tangled and unruly hair is one of the hallmarks of a witch. It's said that even if she tries to keep her hair neat and clean, it will naturally fly out from beneath her scarf or hat, nor will it stay pinned or braided. Legend states that hair holds a great deal of magickal power for a witch (think of how many hex spells require a snippet of the victim's hair). And while her hair doesn't need to be a rat's nest to wield such power, a witch's hair is always compelling to look at or touch. In some way it must be unique: the volume of it, the beauty of it, or perhaps an unusual or radiant color (red or black, anyone?).
Witches like to linger in grocery stores or at the mall. Traditionally, it's said that they liked to linger in the marketplace long after their shopping was done as they could absorb a great deal of usable energy from all the shoppers haggling and fighting over the food and wares. If you lingered far longer than the village's powers-that-be deemed necessary for ordinary shopping, you could be branded a witch and tried accordingly.
Food for thought.
The Weiser Field Guide to Witches, Judika Illes, Red Wheel/Weiser LLC, 2010