I hate playfield toys. Sure, a couple of nice theme-matched pieces is fine, but overall toys are stupid and cheapen the look of most machines.
I hate incandescent light bulbs in machines. They suck all around. They aren’t bright enough and the heat they emit ruins everything they are near.
I hate colored GI.
I hate people who don’t understand what maintenance means and still own pinball machines.
Edit: Overall, I hate this topic.