In Castles & Crusades Where a character, and not a player, has had an experience that could impact upon present circumstances - a Wisdom based attribute check is often involved.
Wisdom checks often help resolve unclear circumstances through hunches or gut feeling. Wisdom is also used to determine surprise, and when allowed - to spot something not normal about a situation.
This is one of the rare instances where the 12/18 (Primary/Secondary) rules (sorta') fall down.
This means that EVERY character (and always Clerics and Druids) with Wisdom as a Prime Attribute will always be at an advantage in these sort of situations.
It is an easy problem to resolve however, if you look at these sort of Perception checks in a slightly different way.
A Character (Fighter, Ranger, Cleric, Wizard, Thief or whatever) has training in such things - whether it be spotting potential threats, noticing subtle things about an opponents demeanor, or sensing an ambush - and such training would 'stem' from the Characters Prime Attribute.
So, the simplest method to adopt for resolving such tests would be to use the Classes designated Prime Attribute - Wizards would use Intelligence, Clerics would use Wisdom, Fighters would use Strength - and so on.
This way every Character would be on an equal footing with no one having a distinct advantage (beyond their Attribute Scores) over anyone else.