I can tell you the magic technique I use but I've never tried it for that many listings.
All you do is give a fake address and have the card go to a stranger. Then you wait 2 weeks. The card will go to whatever address. I don't know what people do with the cards my guess is they assume it's spam then throw it away.
Anyway, after 2+ weeks an indian guy will call you. All you do is play dumb. Say the card never came. They'll verify the listing over the phone for you. The problem is I've never tried this with the cheap $1 forwarding numbers. I use real local numbers that are $5 / month. And I also drip feed fake reviews then do tons of citations to get them ranking.
TBPO, I think 20-30 listings done "proper" with lots of citations and reviews will pull more traffic than 500 that you just verify and do nothing else to. Not to say that your listings won't drive traffic. But it is relevant to competition. If our top competitor has just 4 reviews we'll do 8. If they have 20 we'll do 40. The point is we actually rank and review every listing. I know from experience I'd rather have 1 well reviewed listing with lots of citations and reviews compared to 10 listings with 0 reviews and just a few citations.
So if you have problems and G starts deleting listings... just build a private review network. Then outsource citations and do reviews yourself. After 3-6 months those listings will rank, gain huge proximity and convert like gangbusters.
Gluck - BB
