I first saw a salad spinner in France, back in 1981. I think I laughed. What a contraption ! Why would anyone buy some thing that does that ? I mean, what's wrong with rinsing lettuce in a colander and letting it drip dry ? Well, it never does dry that way, and that's what's wrong.
Unwashed lettuce can be full of sand and the occasional bug, so it must be washed. Excess, or even any, water in a salad dilutes the dressing and makes the salad, well, soggy and unappealing. Crisp, dry lettuce is what you want. The spinner works almost like the spin cycle on your washing machine. The inner basket of the spinner rotates at high speed forcing the water outside against the wall of the bowl where it then falls to the bottom, below the basket. Et voilà, dry lettuce !
By the way, in France, lettuce is commonly called salade. The word laitue exists, and according to the Petit Robert it does mean the leafy stuff we call lettuce, but most people (and markets) use laitue to refer to what Americans call Boston lettuce. Salade includes chicories, lettuces, and other leafy plants. Common varieties of salade in France are batavia (rouge ou verte), feuille de chêne, scarole, endive, roquette, cresson, mâche, romaine, and frisée. Iceberg lettuce is rare here, but you do see it around.
A salade is typically served by itself, with vinaigrette. Once you add anything to salade it becomes a salade composée (salade niçoise and salade grecque are good examples). There are special salads that you will almost always find in cafés and restaurants like frisée aux lardons or scarole aux betteraves or endives aux noix.
It gets even more complex, because une salade is not just lettuce, but can also be the name for a great variety of other dishes that are served cooked or not, than can include meats and seafood, and that are dressed in a sauce. These dishes are said to be mangés en salade, or eaten as a salad. But that will be a discussion for another time. Let's just stick to the leafy stuff for now.
You can crisp up a tired salad by letting the leaves soak in a basin of water for 20 minutes or so before spinning them dry, provided they are freshly separated from the head. And that's a good tip : never take all the leaves off a head of salad unless you plan to use them all. Work from the outside in, breaking off each leaf, and leaving the rest attached. Put the unused portion of the head in a plastic bag back in the fridge, and your salad stays fresher longer (this doesn't really work for iceberg lettuce, however).
When a salad spinner is unavailable, Ken will always put washed salad in a clean kitchen towel, gather up the corners, then go outside or into the shower and swing it around to dry it. This works great provided you hang onto that towel. I have seen salad leaves flying through the air; not a pretty sight.
We've had many spinners over the years. Our current one, an OXO, is great and I think it's lasted longer than any of the others. There is no cord to get tangled or to unwind. The mechanics of the OXO spinner are pretty simple and it works. And it even has a handy brake to slow and stop the spinning basket. Pretty cool.
You can also use the spinner to dry freshly washed herbs. The bowl of the spinner doubles as a wash basin.
No kitchen should be without one.