It would actually work pretty well as a bodyguard, but as an assassin, well, the person has to be sent there, most of the time, and has to have some understanding of the layout and location. Which will typically mean (1) having received a guided tour before or (2) having a companion with eyes at the time. Both of which will lead to at least some question of "wouldn't it be cheaper to higher someone else?" or "how good is the companion?" "how much time is wasted familiarizing this person with the layout that wouldn't be wasted with someone else?" etc., etc...

I have often pondered why I never waste any time wondering about the jeep and credit cards and newspapers in Saiyuki when I will obsessively pick at other things for far, far smaller things. Ithink it's because she doesn't really bother with any worldbuilding. I'm just about finished with the first Black Company book, and noticing the same thing.