I'm the one who posted this. When I was a serious coupon addict (which I'm not right now, but I'm probably going to get back into it again soon), I would collect about 100 papers worth of coupons each week via the newspaper recycle bins.
The key is to clip EVERY coupon, and not just the ones for products you use. Just because you don't use a product, doesn't mean you shouldn't "buy" them if they are free! In addition, sometimes "buying" those items that you don't use can actually SAVE you money on your overall grocery bill. For example, if you "buy" a $1.00 item and save $1.20 on it in coupons, then you've MADE $.20 on that item...that $.20 will effectively be applied to the remainder of your grocery bill, plus you get the item you "bought" for free. Let's say you had 25 coupons for that item...well now you've just gotten 25 free items (even if you can't use them) and you've also reduced the remainder of your grocery bill by $5.00. If you can't use the free items, either have a yard sale, sell them on eBay, give them to friends/neighbors, or donate them to a charity. SOMEBODY out there wants them!
I'll never forget the time that I purchased about 50 packages of Depends, because they were free. I went onto a checkout lane with a teenage male cashier and a teenage male bagger. I could tell they wanted to laugh at my order, so I made a joke about it myself

BTW, I put all those Depends out at my yard sale for $1.50 per package and they were all gone within an hour!
As for what people will/won't buy on eBay, they will buy ANYTHING! If the free items from my stockpile are lightweight personal items, I sell them in lots on eBay. I sell razors, deodorant, lotions, etc. this way. I've even sold certain food items on eBay this way. Most of the food items or heavier items like household cleaners I sell at a yard sale. I sell them for about 50% of their store value and they sell out VERY, VERY fast.
If you don't like the idea of collecting coupons from recycle bins, you can buy them online or you can trade online.