I got caught out once on final trying to ident the Localiser which wasn't making sense. Asked the tower what was up and they said 'Oh its being calibrated and is not working properly'. Had to quickly revert to an NDB app. I definitely scan the NOTAMS now...
I recently saw a NOTAM stating that migrating Geese would be crossing my final approach track at 500ft AGL. How do the Geese get permission to do that?