Refrigerating salad dressingWhile I always refrigerate any leftover vinagrette (for the next day's lunch salad!), those made with oil and vinegar need not be refrigerated if used in a week or so. The main problem is the oil going rancid which is slowed down by refrigeration and by minimizing head space in the bottle. A reason to not want to refrigerate is that olive oil often solidifies at refrigerator temperatures, making it an irritation to use. That said, I'd be more of a dressing made with fresh juices.
We see blood oranges seasonally here in Upstate New York at big stores like Wegmans. They make a delicious and colorful dressing for Mexican and Tex-Mex style salads, though I prefer a touch more acidity from a dash of added lime or lemon juice.