Chris Avellone tweeted about how quickly disguises will be seen through in New Vegas and offered some clarification:
<blockquote>In FNV? Depends solely on what units spot you (dogs and lieutenants) - rank and file won't notice anything wrong.[..]Sneak only affects if the "sniffers" (dogs and lieutenants) can spot you if you're sneaking, no passive impacts on disguise.</blockquote>
And J.E. Sawyer posted about the slow-motion killcam:
<blockquote>It isn't seen after every kill and it's optional.
[..]
I believe it is only triggered when you kill the last hostile within range. So if you're in an extended firefight, it's not going to go off until the last target drops. </blockquote>
<blockquote>In FNV? Depends solely on what units spot you (dogs and lieutenants) - rank and file won't notice anything wrong.[..]Sneak only affects if the "sniffers" (dogs and lieutenants) can spot you if you're sneaking, no passive impacts on disguise.</blockquote>
And J.E. Sawyer posted about the slow-motion killcam:
<blockquote>It isn't seen after every kill and it's optional.
[..]
I believe it is only triggered when you kill the last hostile within range. So if you're in an extended firefight, it's not going to go off until the last target drops. </blockquote>