On: Preventing users from pouring water into coffee machine beans compartment

[tzury]

That's a nice story of how a consultant have ruined the engineer's day.

[jarek → tzury]

You could also say it's a nice story of how a lack of documentation caused pain for both consultant and engineers.

[RyanMcGreal → jarek]

And yet the premise of good UI design is that it should be self-documenting.