Even when I run a storebought adventure, I tailor the heck out of it. I'll look through my various rulebooks, find the coolest, weirdest treasure in there than I can find, and then I'll try to weirdify it up a little bit more before handing it over to the players.
For example, a hoard in one game included a staff of healing. Bo-ring! I mean, there's already a cleric in the party; what do they need more spontaneous healing for?
So I looked around until I found a cooler item: in Relics and Rituals 2, there's a staff that can cast fabricate and major creation and gives a +5 bonus on craft checks. Closer.....
I changed the staff to be instead a magical collection of tools that transformed at a command word into a set of masterwork tools suitable for any job and that could, once set in motion, work independently The tools thereby doubled the effective ranks a character had in any craft skill, up to +10 (e.g., a character with seven ranks in craft: trapmaking could use these tools to gain an effective fourteen ranks in craft: trapmaking). The tools could also be commanded to rapidly build or transform objects, per major creation or fabricate.
I bundled these tools with a collection of other thematically appropriate treasures that suggested the loot of a slain adventuring party (a scalp full of minor fetish beads, an ice-sword that transformed the user into a white tiger, etc.) and then handed it over.
Always tailor -- it makes the game more fun, IMO. Makes the world seem more alive, makes magic more mysterious.
Daniel