I haven't noticed this being a problem since the last patch and IL.
This only seems to randomly happen when a Celebrity with the Refined Palate trait marries a homeless Townie. If the Townie cooks a Normal group meal it can effect the whole households ability to cook Excellent meals for a short period of time. If no one cooks for a while it goes away. Yay! Dining Out!
The solution is to not have that Townie cook group meals if they're not Happy or Inspired.
I think this is just a combination of a glitched Townie meets the Refined Palate trait bug*.
*Sims who use the Quick Be Gone potion, but continue to exhibit the removed trait.
I haven't noticed this being a problem since the last patch and IL.
