Twitter allows meto choose who follows me. If they aren’t in my particular field, or aren’t of benefit to me, or I really have no clue who they are, I block them. If they are on LinkedIn and are a contact, they can ask me why I blocked them – easy to unblock. If they are on Facebook, I’m usually communicating with them in discussions greater than 140 characters.
I don’t buy contacts, I don’t buy email addresses – I find them myself. It isn’t easier to use a bulk system; it is more annoying for the end users and can lead to business being missed by an off-side rep.
My line of work means that reputation is everything.