DLC to me should be worth the points it is priced at. Fable III is a game where some of the DLC is not worth it, because i believe some of it was ripped from the game and sold to us at extra cost. Dye pack anyone, 80 points. Yes it is cheap, but they should have been in-game. 260 points for 1 costume is a rip as well.
But on the flip side, i have downloaded some excellent DLC. GTA IV expansion packs (Lost and Damned and Ballard of Gay Tony) were well worth the points, gave me 15 hours of extra gaming per-pack and had their own multi-player modes. Red Dead Redemption had some great DLC as well, especially the free-roam add-on pack. Oblivion has good stuff as well