Thanks for posting this Tpd5! I needed this information myself; as I'm in a similar situation. Thanks to everyone that replied...this newbie appreciates your insight...and your humor!
I can't say whether you're overthinking or underthinking. In hunt training, the retrieve (to a natural, driven retriever) is an powerful reward. I don't know whether you're in a pet "manners" class or a class where the instructor may be trying to lay a foundation for both competitive obedience trials and basic manners.
Competitive obedience training doesn't not have the built-in reward (the retrieve) that hunt training does. Competitive obedience involves a whole lot of persnickity obsession with detail that does not come naturally to a dog. Almost all dogs need some external reward (treats or play) to learn to like obedience, which is why virtually all top OB competitiors today use a lot of treats.
Dogs, as someone pointed out, are highly situational. Believe me, your dog will quickly learn the difference between field and OB. You might want to take a look at Connie Cleveland's Dog Trainers Workshop website:
In particular, watch her videos of her training her labrador puppy, Nate. She has videos of Nate doing field work and competition obedience exercises. In the former, Nate is working for the retrieve (few or no treats). In the latter, he's getting plenty of treats (e.g., see this video of Nate learning to retrieve a dumbbell and return to a front position: http://www.youtube.com/watch?v=MNOJyyycyV4
Connie Cleveland has goldens that have both AFCs and OTCHs (Obedience Trial Champion)
Connie Cleveland's Golden, AFC OTCH Topbrass Caleb UD, was the only Golden entered in the 2012 National Amateur Retriever Championship.
I would say that her dogs could tell the difference between obedience and field trial work.
Also, you might enjoy watching her videos of her teaching field work to Nate.
Janice Gunn (TNT kennels) also has Goldens with both FC/OTCH titles. She also uses a ton of treats for obedience.
Kelly Cassidy (person)
SR Maple Cassidy CD JH RE (golden retriever)
Alder Cassidy CDX RE (standard poodle chipmunk chaser)
plus the "old ladies" (2 elderly mix-breed rescue girls)