What counts as an opt-in?

I had to laugh out-loud today when I read the final point of Seth Godin’s blog, which stated ‘Assume that unless they’ve notified you otherwise, all prospects are willing to get spam (press releases, phone calls, letters, ads) from you.’

I’ve tried it all when it comes to reaching out to potential customers (cold-calling, canvasing, mailers, emails, promotional products, etc.) and have had mixed results with each approach.  Additionally, I’ve never been timid to reach out to someone for the first time.  Fear of rejection is simply not in my make-up.

Seth’s post made me curious about what it means to opt-in.  If someone give you their business card, does that give you the right to put them on your mailing list? (I think it does)  What about cold-calls?  When we put together a list from the Chamber of Commerce or even the Yellow Pages, are there any rules about who you should or shouldn’t contact?  Is the old ‘throw it up against the wall and see if it sticks’ mentality valid?  I’d like to hear your thoughts.