The fare code is often nested somewhere or plainly hidden. I had plenty of surprises in over 3 years of 1K.
I posted a question elsewhere about SWU when you buy at Orbitz. Clearly that is one example where you can get a CHEAP transatlantic ticket that is a junk fare code like S or so and it will not be upgraded. Same for consolidator's ticket. No info is disclosed by Orbitz about the fare code. Certainly not when you shop or try to copmare fares.