This is one of the main reasons for working as a team. And, as in business, sports and elsewhere in life, a team formed of people who don't all think alike, a team where people are comfortable about questioning the assumptions of other team members, including the leader, is a stronger and more effective team. A team made up of paranormal believers will be more easily misled and thus less effective than one containing a people with a range of beliefs and views; from believer through agnostic through to skeptic. (It's fair to say, then, that a team comprising only skeptics and scientific thinkers would be equally ineffective in investigating the paranormal; they're more likely to miss stuff that people more open to the paranormal might more readily perceive.)
So, from this mundane plumbing issue, I have learned two lessons:
- Don't act on the most obvious cause until you've checked it is indeed the true cause
- Make sure you're working with people who don't all think the same way you do, and make sure you listen to them!