Perhaps 7 or 8 items at once -- to Nordstroms, and from on-line shopping.
As an avid online shopper, I seem to have a perpetual "revolving door" of returns in my possession! Often, the return portion is the bulk of the order. I don't feel badly about this as it comes with the territory of online shopping, and I think that vendors who understand this and make returns easy will come out ahead in the long run.
Also, I will often return multiple items to brick and mortar stores if they don't look as good at home as they did in the store (darn those skinny mirrors!) or if they don't pair with other items in my wardrobe nicely. I think that if you're working within the constraints of the store's return policy, there's no reason to feel badly or guilty about returns regardless of the number of items.
