People with negative taste can make things that look really nice, but they also look very plain. I think the founders of Google have negative taste. John Gruber, as far as I can tell, mostly does. Same with Paul Graham. (As do I, for that matter.) People with negative taste make things by trying something very simple and then stripping away pieces ... See more
People with negative taste can recognize people with positive taste and hire them. People with no taste, on the other hand, fail to see the difference, resulting in disasters like the graphic design department of American Airlines.
Negative taste is the ability to tell when something is bad. Positive taste is the ability to make something that is good. Indeed, one might even say that there is only one kind of taste and positive taste is simply negative taste plus skills.
People with positive taste, on the other hand, can make things that genuinely look good. This gives them a lot more freedom in their designs (they can use colors other than white!). Truly good designers have positive taste. Unfortunately for people like us, Apple seems to have hired most of them and put them to work building fairly bland web sites.