Actually, in all cases that have been stated here - you DO get an item. Unfortunately, it's not what you were expecting, so you don't notice it in your inventory.

And the game does tell you what you get... Again, unfortunately - most times the little notification on the bottom right of the screen is quick and dim, or is quickly erased by an auto-save or a video clip.

Yup, you get a rusty sword from the dwarf. Melitele's heart is in your inventory (if you completed the quest properly). Thaler sends a forumla for a potion ( Petre's Philtre). Most times you seem to get junk, so if you have the choice - take the cash...