I'm in the Bay Area, and run a business myself. My address is listed as a contact with a number of associations. Some of other members of these groups seem to think that adding the full list of contacts to their mailing list is a service to the community. Some are companies that I've corresponded with in the past, who about once a year seem to take their entire list of emails and slam them onto to their new mailing list. Others (recently a spate of real estate companies) seem to have found my address by some other means.

Sometimes I've given them the address for some other purpose like notifying me for when a special order comes in or to register for a specific event. I'm not using "spam" in quite the legal sense --- I'm sure it could be argued that I have a pre-existing relationship with some of these businesses. But unless I have explicitly checked a box that says "please send me email about your business until I tell you to stop", I consider these unsolicited commercial messages to be spam.

There's a difference between expecting to receive an email (e.g. an order confirmation) from someone, and expecting to receive an endless stream of emails from them.