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.
The female bandit's valley girl speech in 4 includes a long rant about going to the hootenanny. It's unbelievably funny because her dialog is about a century ahead of the setting.
Evil Is Sexy - The female bandits in 3 and 4. Possibly 1 and 2, of course YMMV on that.
Possibly the female gunslingers in 2 and 3. They aren't evil by the plot standards but they do work and kill for money, so...
They Changed It, Now It Sucks - The original Westward was done in a purely 2D format with an overhead view. When the second game was announced, it was shown to use a fully 3D engine with an isometric view. The game was also redesigned with an experience and quest system used to unlock buildings and upgrades. A town happiness system was introduced which could either help or harm the town. The main setup also featured the Hero character, a selectable main character that didn't need a home and served as a cross between citizens and gunslingers. While this trope was mostly averted in the long run, the initial reaction to the sequel change was surprising.
Westward Kingdoms may also apply as it completely shifted everything to a medieval setting with a new art style. Much of the humor seemed to be removed and the music felt less cheerful.
Uncanny Valley - some of the 3D models starting with game 2. They're all fairly simplified to start with but many have these odd, unsettling smiles on them. It's just creepy.