Some idiot newspaper, which doesn't deserve a link, noticed a few comments by a Spanish priest run in the Vatican newspaper and then decided to run their own piece declaring the entire Catholic Church as against all Halloween celebrations everywhere. This is nonsense. I don't know of a specific doctrine with regard to Halloween per se, but let me mark out the line as I see it.
As a part of celebrating Our Lord's victory over death, and the working out of that victory in the lives of the saints, a certain amount of lampooning death is fine. The line is crossed when death is glamorized or adored, or is portrayed as the victor. The entertainment industry crosses this line all the time, of course, but this merely means we ought to reject their products, not the entire holiday.
A little kid in a skeleton costume makes Death look silly. Stupid mass media, like the Twilight mess, makes Death look, well, like a school project involving glitter gone wrong, which I suppose ultimately makes Death look stupid, or at least unmanly, but unfortunately the premise of falling in love with the damned will only result in trouble for anyone influenced by it.
Of course I'm not particularly interested in Halloween, but it strikes me this is the sort of thing children need as part of an inoculation against the world. The entertainment, not to mention the politics, of this world begins to seem pretty silly if you've been poking fun at Death for years.