These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Even Better Sequel / Growing the Beard: The series' gameplay, graphics, logic and overall quality tended to improve as the series progressed, with KQ VI generally being regarded as the highest point of the franchise. However, KQ VII had a mixed reception, though positive in general, and KQ VIII was a huge letdown that ruined the series.
Fanon Discontinuity: Mask of Eternity was not well-received by the fanbase, to the point where it's debatably In Name Only. Even the old-school Sierra staffers distance themselves from it.
Narm: "A POIsonous snaaaake! A POIsonous snaaaake!"
What The Hell, Casting Agency?: Lampshaded in a Let's Play of King's Quest V (the CD-ROM version of the game was voiced by Sierra employees, with varying degrees of success. Sierra learned their lesson, and pioneered the concept of Hollywood actors voicing computer games.)
That being said, they still kept developer Josh Mandel as Graham for VI (since he's usually considered the one employee who actually did a pretty good job with his VA) and Mandel has been gracious enough to lend his voice to the fan-done remakes.