If it’s free, do you just take it? and if you do, take it all?

Since I started paying more attention to the types of things one can get for free via manufacturer or store rebate or coupon use, I have been wondering about two issues:
1) Should I get the item just because it’s free? For example, if Walgreen’s (what I have locally) has Beano free after rebate this month, do I just get it because it’s there? But I have never had a need for it in the past. Then should I get it just in case? For me the answer to this has been fairly easy: No. I am a minimalist and I tend to have available only those things I know I will need in the future. I will stock up on the needed items but I can’t stock up on things I don’t need just because they turned out to be free.
2) If I need it, or have some use for it, how many items should I get? I like to refer to this as “freebie greed.” When you find an item that you can get for free, do you clear out the shelves? or do you leave some for the next person? And if you end up taking items in excess of what you can realistically use, what do you do with it? I have seen this phenomenon so often in the bargain forums, it sometimes leaves me baffled. For example, I read about this single guy who visited all of the grocery stores in his town (from this nationwide chain of stores) because he could get free canned soup. He ended up getting in excess of 300 cans. A common argument for people who do this is that they give it away to friends or family or to charity. That’s a valid argument in my book. But what about the next person who went to the store and couldn’t take advantage of the deal because someone had cleared the shelves? Didn’t they deserve to take advantage of the deal as well?
I don’t think there are clear answers to these questions. To me, it seems it’s almost an ethical issue. Do you take it since it’s free and if you do, do you take as many as you can?
What would you do?