[Xaccers]

I think it's a difference of sublty and style.
Dali is more in your face shouting "Cooooeeeeeee! I'm a surrealist, aren't I special, look at me everyone, over here!" while Giger's artwork is like someone calmly sitting in the corner reading a deep book.

Similarly if I compare Boris Vallejo's artwork to that of his wife, Julie Bell, I much prefer his, simply because of her use of "metal skin" which I think detracts from the quality of the rest of her artwork, especially when done in silver/chrome. She also seems to have trouble with angled hips, or maybe it's the models she uses...