Academic guilty conscience.
As an undergrad, I was a comparative literature major. This is basically like being an English major plus foreign languages. I concentrated in 20th century French and Italian writers, specifically Italo Calvino and Georges Perec, and it was expected that I'd read everything in the original. Since then, reading translations when I could understand the original feels to me like a cop-out, as if I were reading the Cliff's notes.
I won't deny it. Who among us (and by us I mean lit nerds) hasn't looked up from their weighty tome, scanned the other passengers on the bus, and thought, Who else would read this? Reading in a foreign language, you add, And who else could?
Reading in a language you don't totally understand is a little bit punk rock. The experience is rough around the edges, unfinished. You're taking on a task for yourself — the work of rendering a foreign text comprehensible — that someone else could have done better, but you know that going in. It's a choice you've made, to sacrifice professional polish in exchange for a greater sense of control and full understanding. Think Ramones; think Linux.
This is more of a rationalization, really.
Contributing to the discussion.
In the various internet forums for this 2666 group read, the question often comes up: What is this like in Spanish? Does what I'm noticing come from Bolaño or the translator? I like to know for sure — that's my foreign languages and literatures training again — but it also gives me a different perspective that is interesting to the other readers who are participating.