I am on a low carb diet (which seems to be working really well), so I'm avoiding sweets, potatoes, and things made with flour. The other night I was in one of those fabulous bakeries in NYC (bread! pastries! cookies!) and was really tempted to get something, but decided against it because I didn't want to mess up my diet only two weeks in. I was REALLY upset when I woke up and realized it was all a dream and I could have had those goodies with no consequences!
I have a lot of "forbidden food" dreams when I'm dieting. Only it's usually that I've just eaten an entire cheesecake or something and I'm overcome with remorse. Then I get to wake up feeling relieved that I didn't really eat that!
For me, it's shopping dreams, but the weird thing is, I always remember exactly how much spending money I have IRL, and I'm careful in my dreams to make sure I don't go over my limit.