Eberron gnomes are taught from the cradle to lie and scheme for social position, and engage in any plot or subterfuge short of violence to get what they want. Lying comes as naturally as breathing, and what a gnome says they want and what they actually want are unlikely to be the same thing (unless being open is the deception). The most terrifying words a gnome can speak are, "I can get that for you, I just need a small favour..."
The gnomes decided it was reasonable to police themselves with a secret police force, accountable to no one, that employs numerous assassins with a license to threaten, maim or kill anyone who perpetrates violence or does anything to threaten their sovereignty, social or political order.
Which they are all very comfortable with, since where the line is drawn is crystal clear to them. However the gnome homeland is probably one of the most dangerous places an adventurer can visit, although there are usually warnings before outright assassination. It will start with a whispering wind or message warning them that what they are planning is a very bad (and how did they know what you were planning anyway), and maybe escalate to a debilitating but probably not deadly poison in the PC's drink.
I'm actually kind of ambivalent about them, because I think writing adventures for the gnome homeland would be a lot of work. But they are a far cry from kender and tinker gnomes.
