Exactly as the topic says.
Are there missions that you worked your ass off on and you get such a terrible reward that you just want to punch the guy who gave you that reward?
I can name some moments off the top of my head:
PMD Sky - Escort to Dark Crater. I got an all but useless power band. And I went through 4 reviver seeds and a bunch of oran berries.
PMD Sky - Southern Island fleeing outlaw mission. Retried about 5 times. Got a few hundred poké and some mostly useless TMs.