O'SToPotD: code smell

O'Shaughnessy's Turn of Phrase o' the Day is "Code Smell":

A code smell is a hint that something has gone wrong somewhere in your code. Use the smell to track down the problem.

Highly experienced and knowledgeable developers have a "feel" for good design. Having reached a state of "Unconscious Competence," where they routinely practice good design without thinking about it too much, they find that they can look at a design or the code and immediately get a "feel" for its quality, without getting bogged down in extensive "logically detailed arguments".

Excepts taken from Cunningham & Cunningham's Extreme Programming Roadmap

Here's an example usage from Smashing Magazine:

Nested tables are code smell that a website is stuck in table hell. The number of lines of code is endless, and the complexity is overwhelming. Tables are far from clean code and don’t bring anything semantic to the content unless you’re dealing with actual tabular data.

Now go forth, spread the good word, and be wary of the smell.