Obvious issues can betray the presence of subtler ones

Recently, I stayed in an Airbnb. At this Airbnb, the shower's hot and cold were reversed. Initially confusing, but once I realised this I could use the shower with no issues.

I later realised that the bathroom tap's hot and cold were also reversed. Again, no real issue.

I went on to discover (due to the uncharacteristic warmth emanating from it) that the toilet's cistern was being filled with hot water.

Obviously, flushing the toilet with hot water is a waste of money and energy, and a bigger problem than reversed taps. I suspect that the cause of the reversed temperature tap/shower was probably the same as the bizarre plumbing that led the toilet to be filled with hot water.

Thus the importance of root cause analysis: investigating minor but more obvious issues can help us uncover subtler but more significant mistakes.

There is rarely just one bug!