I recently read an article on change.org about what type of bag you should choose at the supermarket. The author, however, write that it isn't as important what type of bag you use as what's INSIDE the bag. Condiser a bag full of meat, potatoes, tropical fruit and soda and another bag with a vegetarian diet with soy protein and produce coming from your country. It takes 113 MJ (megajoules) to get that first bag of groceries on the dinner table and 24 MJ for the second. On the other hand, it only takes 0.5 MJ to produce and dispose of a plastic bag. Therefore the energy saved by a family of four eating a diet from that second bag of groceries would be enough to manufacture 186 plastic bags or drive the average American car (meaning: big) for 15 miles (24 km). And all this backs up what I wrote a couple of weeks ago about the harm eating meat does.
Ok, so even if we just buy dry beans and local fruit and veggies, we still have the plastic vs. paper dilemma. It seems (according to that article) that it takes 20 times the amount of energy to produce a paper bag than a plastic one. But you can easily recycle paper bags while plastic ones take centuries to decompose, they're dangerous for wild animals and they create other problems, like blocking public drains. And so there's no doubt about it that reusable/washable bags win hands down.
There are all sorts of possibilities for reusable shopping bags: cloth ones, juta ones, more resistent plastic ones, etc. In the United States reusable bags are relatively popular, but Italy (or at least southern Italy) hasn't quite caught on yet. Sometimes I actually have to argue with shopkeepers or cashiers because they insist I use their plastic bag. I could understand slightly if they had a bag with their logo to give them advertising, but generally they're just anonymous plastic bags.
One problem I often run into is when I decide to buy something when I'm already out and about, without my collection of washable bags. Those who usually move around by car can just keep their reusable bags in their car, but it's a bit harder for people on foot to bring around a bunch of cloth bags. Last year I was given a very nice gift, the ChicoBag. It's a bag made from 7 recycled plastic bottles, is super light, and gets closed up inside a little pocket sewn on the inside to bring it around. You can't use it for really heavy things (I had to resew some of the seams after I put too much weight in it once), but it's really convenient to carry around in your bag all the time for when you make a spur of the moment purchase.
Those bigger plastic shopping bags are easy to reuse in other ways, like for your trash or to carry around other stuff. But my main problem were those smaller produce bags. They get dirty, and so are hard to recycle, and they're too small to really reuse for many things. And just look at all that plastic used to bag up a single cucumber! Ridiculous! Then I saw some produce bags made of organza or nylon mesh on the founder of the website Cloth Pad Shop (where I sell cloth pads and other things)'s personal website. It seemed like a great idea, so I copied it. I got some nylon mesh and added a drawstring recycled from the same pyjama pants I made my potholders from. Next time I'll use some lighter (and prettier) ribbon or something for a drawstring. They looked at me kind of funny when I asked to use these bags at the supermarket (though I'm used to this, being a "weird" foreigner who always does things "differently" than everyone else!) but they didn't have any problems with them. And just look how pretty groceries are with these bags!
There are, however, people who put plastic bags to good use. For example, there is a seller on etsy (which unfortunately is not at all used in Italy, despite the fact that there are exceptionally wonderful things there) that makes jewelry, bags, hats, etc from crocheted plastic bags, as well as other things made from recycled plastic bottles and cloth. I bought one of her bags and some jewelry, and she even sent them to me in the coolest boxes she made out of folded magazine pages. Check it out!