|Douglas Muir 406|
[I'll add this as an example for the Skill and feat taxes: The Shadowdancer requires skills in Perform (Dance), which is fitting considering the concept. However, that skill is NEVER used... at all. The Shadowdancer doesn't substitute a regular skill check by a Perform check for any of its abilities.
That's pretty bad, but it's also (unfortunately) pretty common. See, e.g., the Sanctified Prophet, who has to blow ranks on Profession (merchant) -- which not only never gets used, but may actually consume half the character's skill ranks for several levels (since he's likely to be a cleric, with just 2 ranks/level).
My personal candidate for "worst skill/feat tax" is the Halfling Opportunist. This poor little guy has is forced to waste a feat slot on Defensive Combat Training. That's (1) a feat that's really feeble under the best circumstances (it lets you use your hit dice instead of your BAB for determining your CMD); and, (2) is even more worthless for a halfling rogue (since you're going to have lowish Str and a negative size modifier, which means your CMD is going to be awful no matter what you do).