Well I don't know if it qualifies as a "preferences dialog" but there is one glaring example of poor ui design that's annoyed me repeatedly, and that's in use in several places in the standard ui. This is a case of "looks good but gets in the way of getting the job done"

I'm talking about the time picker. Quick way to see this is to add a new alarm, and set the time. Do this and you're presented with two lists one with 24 and one with 60 items. Yes it looks good, but it's nowhere near as effficient as an numeric keypad and a text field would be.

Further problems with the time picker:
- There is also no wraparound in the list so you can't go from 00 minutes to 59. Meaning when it suggests x:00 but I want x:50 i'll have to scroll past 50 entries in a list.
- No keyboard input.

Lesson learned:
When making the user pick from a list, if the list is long then consider alternatives.