Aye, there are several reasons for why it might be unwise to just announce yourself openly the moment you set down foot.
I know this RPG deviates from GW's original material a bit, but I still find the following excerpts helpful to convey an idea that does exist in Dark Heresy, too.
#1 Don't alert the enemy
"An Inquisitor has, in theory, the whole of Humanity to command to his cause. He can requisition Space Marines and soldiers of the Imperial Guard, call upon specialist warriors such as Grey Knights and Sisters of Battle. And yet, the nature of his task means that all too often he must rely upon his own strengths and resources. If he fears a planetary ruler to be under the influence of the malign beasts of Chaos, to whom can he turn? If the populace of a world has risen in revolt against the Emperor, who will provide him with succour? By necessity, the Inquisitor works mostly in the darkness and shadows, his presence not recognised, his works unseen. Thus the Inquisitor and his warrior band know that they must stand alone against the horrors of the galaxy, for they can trust no one else."
- 6E Codex: Inquisition
#2 Don't presume that flashing an Inquisitorial seal will get you anywhere, every time
"The basic operational unit of the Inquisition is the Inquisitor. In an Imperium that groans under the weight of gargantuan organisations and an impossible bureaucracy, the Inquisition is unfettered by such considerations and is free to operate where and how it sees fit. With an open remit to combat threats to Mankind, the Inquisition operates outside of the other Imperial organisations, though it has absolute authority over them.
In practice, the Inquisition must be more political than its mandate allows. Though their power derives from the Emperor himself, and even the High Lords of Terra are not above their scrutiny, the Inquisition must also rely on the other parts of the Imperium for resources. The Inquisition has tremendous amounts of power, and has access to troops, weaponry and archives beyond most other Imperial organisations - yet it must still receive these from the Adeptus Astartes, the Imperial Guard, the Adeptus Mechanicus and others."
- GW Inquisitor: Thorian Sourcebook
#3 Every Inquisitor has rivals within their own organisation
"Given the secretive nature of the Inquisition, the way a cell operates is very much built upon keeping the members secure and to protect them from outside recognition. Many Inquisitors do not work openly, and simply identifying another Inquisitor can prove difficult. At some point, as suspicions are aroused, an Inquisitor will have to make the choice whether to declare himself - risking discovery by a potential foe, but also gaining a possible ally. If two covertly operating Inquisitors encounter each other, the manner of their meeting will determine their reaction."
- GW Inquisitor: Thorian Sourcebook
Of course, there are also more martial-minded Inquisitors who act openly, arriving with their household army to flush out cultists, yet as such a hard-handed approach runs the fear of simply scattering the malcontents like rats rather than succeeding in approaching the root cause of the issue, such tactics may not work every time, or only when a world is already in open rebellion, forcing the Inquisitor's hand. That being said, there is also the option of another Inquisitor "piggy-backing" an overtly acting colleague's zealous crusade by acting in the shadows, using the confusion and chaos to pursue their own mission, like Jaq Draco in the Inquisitor novel.
Edited by Lynata, 22 December 2013 - 09:05 PM.