Acrid taste on King Crab Legs
Fresh seafood should smell briny, like the sea. It generally should not smell strongly in any way--not in a "fishy" way, and not like ammonia.

According to the US FDA, you should not eat seafood that has even a fleeting, minor smell of ammonia:


  Uncooked spoiled seafood can have sour, rancid, fishy, or ammonia
  odors. These odors become stronger after cooking. If you smell sour,
  rancid, or fishy odors in raw or cooked seafood, do not eat it. If you
  smell either a fleeting or persistent ammonia odor in cooked seafood,
  do not eat it.


The scent of ammonia in shellfish is a strong indicator that it's gone bad. When the crab meat begins to decompose, the byproducts create the scent of ammonia. Even thought the scent was minor (you could smell it, but not your wife), this would still indicate that the crab legs had begun to rot. 

Crab legs are generally flash-frozen immediately upon harvest, and kept frozen until you buy them and bring them home. This keeps them "fresh" because they spend very little time in the danger zone. 

Likely, in transit between the dock and your home, the crab legs thawed, spent excessive time (more than 2 hours) in the danger zone, and have spoiled. I would not expect the refrigerator storage to have caused this alone, unless there was also additional non-frozen time before you purchased them.