I find myself not making as many side salads these days. I only buy pre-packaged salad mixes anyways. "Mainly Romaine" is always my choice. I was turned off by some major makers of salad packs not rinsing all the dirt off before packaging. That didn't help. I bought a salad spinner and used it on that company's bad tasting salad package. After one thorough spinning, the salad still had a dirt taste to it. I expect major makers of salad packs to rinse their salad thoroughly so that I don't have to salad spin them.
As some have mentioned, you should rinse packaged salads anyways just to be safe from food born pathogens. You can rinse spin packaged salad and still get food poisoning.
I should, but don't usually spin rinse packaged salads (if they do a good job at rinsing before packaging). I know, I'm taking my chances.
There are only a few nationally known brands of packaged salads. One of them let me down big time (dirt taste remained after rinse spinning).