I think we need to consider
Sting's range more closely than Aragorns supposition that Sting was detecting
orcs on
the East Bank.
Aragorn may well have been wrong:
Ugluk and his ill-led, ill-fated crew were wandering around nearby I recall. Its not clear how far, but could be just a couple of miles I think.
Anyone volunteers to post in detail on this? There's got to be a stack of examples...
On orc-snozzles...
The range of an
orc nose may well vary. From the tracker mentioned in
Mordor, you get the impression that he was a specialist, possibly with a genetically engineered nose. However, the
Moria orcs will be well-used to a lack of light and would therefore have other senses that are more well-developed. There is little to suggest that orcs smoke, but given
dwarves are keen on it they would be familiar with the smell from
Balin and co. As an unusual smell for Moria, it would be readily detectable. Had the air within Moria been wholly still, diffusion would be limited. But the cunning dwarven ventilation amplifies the dangerous nature of Gandalf's fix. Although the smell would remain strong at the scene of his misdeed for some days, traces of it would rapidly
travel some distance. Perhaps Gandalf's harsh reaction to Pippin is really an expression of the guilt he is himself feeling, for his own reckless behaviour?
I wanted to blame Gandalf's act for putting
Gollum onto their trail. Unfortunately Gollum is already following them at that point, so it doesn't work.