Undead and Feint

[Storm Raven]

A skeleton of a bugbear is NOT a humanoid. See the SRD, skeleton template:
"The creature’s type changes to undead."

So even if you had a skeleton with intelligence, you'd take the -4 penalty. A typical skeleton has INT 0 though, so your feint just fails.

Actually, a skeleton has an Intelligence of "-", which is different from a 0.

 

[mcgeedis]

OK, some more examples.

Vampire?
Wraith?
Mummy?
Shadow?
Lich?

Are any of these guys subjected to Feint? If not, then Improved Feint is not the feat for me. I'll just have to flank the baddies instead, I guess....

 

[nittanytbone]

Dude. Just look in the SRD:

*If it has anything other than "Type: Humanoid," you take a -4 penalty.
*If it has intelligence of 1 or 2, you take a -8 penalty.
*If it is nonintelligent, you can't do it.

Look at a creature from your list. See what its type is (probably undead). Check its intelligence score (Vampire? Probably not that stupid). Apply penalties.

Also, FYI, feinting is incredibly suboptimal. SA relies on many attacks (such as through TWF or Rapid Shot) to get its damage. Feinting precludes full-attacking. Unless you have Invisible Blade levels (I think that's the PrC that lets you feint as a free action), its worthless.

 

[Boondoggle]

All of the monsters you listed have an intelligence greater than 2 and are of the undead type, hence you can feint them all, at a -4 penalty. As was mentioned, generally, feinting isn't the strongest use of sneak attack. However, if you're going to be mostly rogue with a dash of fighter, then your iterative attacks won't be very effective, in which case, feinting can be a decent strategy, albeit still far short of flanking. If you want to be more roguish, you should definitely consider between 5 and 10 levels of the Skullclan Hunter PrC in the Mini Handbook. It lets you sneak attack undead, grants immunities, gives permanent PFE and overcome any undead's damage reduction, all in the first 5 levels.