I just want to reiterate a few important points:
1. You can use two coupons on a BOGOF sale regardless if the items rings up full price + free or 50% + 50%. That is, provided your store allows it.
2. The stores LIKE for you to use two coupons on a BOGOF because they get reimbursed from the manufacturer for the value of the coupon (plus some small fee) on an item that they would normally have to "eat" the full cost of.
3. Most of the people who EXTREME coupon would have the store order stock for them. They wouldn't go into the store expecting to buy 300 boxes of cereal. So they wouldn't be taking away stock from regular customers. Personally its the MODERATE couponers who I find take away the stock. They don't have enough coupons to warrant the store preordering things for them, but they have enough coupons to wipe out the shelves.

I just try to shop on Sundays to have the best chance of getting the sales items.
4. Would an extreme couponer go to all the trouble of matching the deals, etc. and then donate them (on a regular basis)? I think yes. For many of these people I think the thrill is in the hunt!
5. I don't think all the people are obese on the show. I know the twins weren't. I don't think J'aime was particularly heavy? The lady who had to bring her 4 kids to the store because her sitter was late? She wasn't obese?? There were others, but I can't remember them all.
I am not justifying all the extreme couponing because I think that everyone I have seen on that show has WAY too big of a stockpile. I just can't imagine eating all that food before it goes bad. I know people donate a lot of what they get, but even the people that were donating their purchases that day had HUGE stockpiles.
But, I think couponing can be a great way to save your family a lot of money.
Maggie