How reliable are scout reports?

[Corwin]

ceremony said:

There are no commanders with Glamour but without Stealth. Glamour gives a unit/commander an automatic Stealth +25, as well as the Glamour advantage of being unseen in friendly provinces.

Right, but my point is that such combo gives you ability to build castle while not being detected by enemy, based upon what people said in this thread. In competitive MP games people have a lot of scouts, and if you see the single enemy commander hanging around certain province for several turns, you know that there is a good chance he is building a castle there. And such privince is a good candidate for the attack with remote summon or whatever you have.