I was 100% against cold shoulders also, but then I saw a couple that I did like--they have a particularly straight and structured cutout. This is how I ended up with the same cold shoulder sweater that Angie has. (PS, If you remember that she had to wait a while for her size to come back in, it wasn't because of me...mine's a size up from that. Just sayin'! ) It also happens to look really Mod on, and I love Mod... I have one other CS top with the same factor--but I don't plan to add any more.
On the other end of the CS spectrum, I am very averse to the type that has a droopy line to the openings. There is range of these, with some being a lot more unflattering than others.
Ruffles are a similar thing--some I quite like, others I'd never ever wear. It really depends on the size, arrangement, and so on.
Bell sleeves are a yes for me. No shorter than 3/4 length sleeves for those however.
As for some big trends I won't do, these include off-the-shoulder for the impractical and busty reasons others have noted, rompers, overalls/dungarees, slip dresses, most wide-leg pants, the white sneaker thing...and for the love of Pete, those terrible, awful slide shoes that look like bedroom or shower slippers--especially the furry ones. Open toe or not. I don't care how expensive they are!
I should probably add mules as well, because although I don't mind the looks of many of them, I remember the noisiness of past pairs and don't want to deal with that again.
Oh, thought of another. Bomber jackets. Not a good cut for this busty, petite hourglass. And I am never going to be in love with white jeans.