I'm an unrepentant power gamer. I can't help myself, I have a logical, mathematical mind that looks for advantageous combinations and synergy.
However, I use my powers for good instead of evil. If I want to make 'the greatest swordsman who ever lived', I'll do that. If instead I want a smooth talking diplomat who considers combat something handled by 'his lessers', I can do that just as efficiently.
That said, I think I could have fun in your campaign. You just have to see the proper context, and some concepts don't work.
And just because its published in WotC books does NOT make it official. I mean, Miasma, for the love of Gary! Miasma!
Here's my guidelines, even in my generic module-led campaign that I'm doing right now. You can have anything in the core. PHB, DMG, MM. And MM mostly for conjured monsters, companions, etc. I really don't like ECL races.
Anything else has to be cleared by me on a case by case basis. Every spell, feat, class, and item. Assume nothing. I'm fairly generous about what I let in, but if it sounds too good to be true, it is.
On the other hand, I will work with a player to make them happy. What did you find offensive about the class - something mechanical or flavorful? Is there any way you can remove or alter the class to let him get what he wants but keep out what you don't want? Or are these the exact same thing.
For instance, I hate the Shadowdancer class as written. It has no place - I have no idea what a shadowdancer is. I have no idea how hide in plain sight works. Now if you redefine the class to be members of a secret society that can channel in bits of the plane of shadow around them by means of secret rituals, then we may be making progress. So someone who REALLY wanted HIPS might be able to talk me into it, as its the flavor (or rather the lack thereof) of hte Shadowdancer that I don't like.