Chosing the right salad seems simple and for the longest time, I just based it on calories and the dressing. I always chose vinaigrettes over creamy and omitted croutons when I served it, and triple washed it even though it says "pre-washed" on the bag. But recently I discovered if you buy the bag that's the flattest, the air was sucked out of it when packaged and it is the most fresh. When the greens age, they give off gas which makes the bags puffier; therefore, they go bad quicker. See if you notice this during your next grocery shopping trip.