To me, Rogues are much more than just a mechanical class definition. Rogues are the non-magical wizards of a party. They have they're tools, abilities, and, most importantly, INTELLIGENCE. A rogue's strong point is in their MIND, not their feats, AB, Str/Dex score or any other mechanical tidbit.
Naturally, a Rogue isn't gonna do nearly as much against a skeleton or zombie as a fighter or mage of equal power. That's just how it works. Part of being a rogue is knowing yourself, your abilities, your tools, and your ENEMY. Know they're strengths and weaknesses, know what makes them difficult to deal with, know what makes them a pushover and KNOW when to back the **** off. Staying to fight to the end is admirable, but stupid, and rogues are far from being stupid (usually).
Moral of the story: Rogues more than likely lose to undead greater than or equal to their level. Once you realize this, stay away from them. Pick fights that are advantageous to your abilities and you'll be fine.
And remember, you're one of the few that can look at a Fireball and laugh. Use it and abuse it.