When I wake up from a good dream, like I have this morning, sometimes I feel a bit unhappy because none of those good times were real.
I could have done without real problems entering even an imaginary place but in a way that made it better, because it made it (seem) more real. Which, yeah, also made it worse in the end.
It's weird. When I wake up from a nightmare, after getting over the initial feeling it gives me, I'm usually kind of happy about it. I even remember a lot more of them than I do my good dreams.