Lists, categories, and tables should all make sense. There should be a purpose of having the lists, and they should be verifiable. We do not need a meaningless list.

First of all,

Do not make lists that have too many listees. For example, no making a category of people who have ears. Unless you were to have your ears burned off or cut off somehow, ALL people have ears!! And there is no benefit to it. Same goes with listing all African Americans, females, or White people. Are those lists even necessary? How about making a list of them by profession ("Category:American musicians of European Descent", "Category:Women computer scientists", etc.)?

Second,

There should be a solid backing. There is a fixed definition of a living person or a personal computer. however, some classifiers, such as a hero or a rich person, that have no solid definition. For example, a hero can be a person that fought in a war, or a person that learned the Heimlich maneuver. There is no fixed definition, and many people will battle and disagree over whether or not President JFK was a hero.

The term nerd is a good example. People have argued over its definition, whether or not it was derogatory, and what activities are nerdy or not. Listing all the "nerds" in the media would be a huge chunk of original research, and would spark endless edit wars and debates on the talk page (this story was true, until they deleted the list from the article.)

The way something looks or sounds is highly opinionated, so avoid it.

Do not interpret songs or films. Examples include an article on songs about tequila, or List of films by Gore.

Third,

People shall have a reason to stare at your list. A list of songs that have the sound of the laughter of children, the sound of Morse Code, or the sound of breaking glass, is entirely unconstructive and pointless. A list of computer programs whose names are offensive to the disabled is up there, too.

Fourth,

Do not be irrelevant. A list of pianists who played with one hand would be relevant. A list of pianists that are missing a uvula is not.

Fifth,

Do not make lists whose sole purpose is to prove or disprove a point. It is okay to create a category for females in computer science. There are many reasons to have such a list. But, it is NOT okay to make a list of gay Jewish blacks who made more than a million, or a list of white people who kick butt at hockey.

And finally,

NO ORIGINAL RESEARCH!!!!!!!!!!!!!!!!!!!!!!!

EXAMPLES

OK NOT Okay
List of British actors list of actors who talked in a British Accent (reason 2)
Deaf Musicians Musicians without an appendix (reason 4)
Scientists Geniuses (reason 2)
List of computers List of pencil sharpeners (reason 3)
Businessmen of Syrian descent Gay muslim businessmen (reason 5)

See also