I agree that the issue isn't that they are regifted gifts (and I, too, wonder how you know), but that they aren't nice gifts and you don't like them. If she received an emerald ring and gave it to you because she already has one and even though it cost a lot more than she would normally spend, would you mind that?
I don't get the whole horror over regifts. It's one thing if someone is just passing on junk when they should be doing better. But that would be just as true if it were something cheap and crummy that they bought. [By "cheap," I don't mean "inexpensive" -- I mean stingy in context of your resources, the occasion, the relationship, etc. Some inexpensive gifts -- like handmade ones, or just something the person will simply adore that happens not to cost much -- are wonderful and far from "cheap."]
I get it about used and discarded items, books with inscriptions in them, items that don't suit the recipient any more than they suited you, things that you think aren't good enough for you, and of course things that the recipient knows you got as gifts yourself -- especially from them!
But a strict never never no re-gifting rule seems silly to me. What about a book or DVD or CD that you already happen to own, that you know someone on your own list would just love? Do you have to donate the one you got and go buy her a new one? A jazz CD when you don't like jazz, but you know that the recipient adores it? A game for a game system you don't own, but the recipient does? A really nice pair of slippers that isn't your size and can't be exchanged? A really nice box of some gourmet food item that you're allergic to or that isn't on your diet? A perfectly nice bottle of perfume or wine that maybe you would even love to keep, but are -- reluctantly -- willing to part with because your gift budget ran out before your gift list? I've regifted some stuff I really liked -- a lovely creamer and sugar bowl come to mind; I liked them a lot, but I had way more sets already than I'll ever need, so I gave them as a gift to a young couple I thought would like them as much as I did. How on earth would they even know someone else picked them out, not me? I think that my son and DIL might do that with some wedding gifts that they got so many duplicates of and that can't be exchanged. I hope so; makes perfect sense to me.
I think the point is just to give a gift with the spirit of generosity and thinking about what will truly please the recipient. Whether you shopped for it or it found its way into your possession some other way doesn't matter, in my opinion, as long it's a good choice for the recipient.