Categorization is a useful tool for finding and correlating articles. However, sometimes we tend to overcategorize; the more categories an article is in, the less meaningful all of them become. Hence, based on existing guidelines and WP:CFD precedent, this page lists types of categories that should be avoided. If created, categories of these types are very likely to be deleted.

Not objectively defined

Examples: Tall people, Notable architecture, Famous songs

It is vague how tall a person should be to be part of this category, and hence it is not a useful categorization. In general category should never contain words such as "famous" or "notable"; it is assumed that if the subject is not famous or notable, it doesn't belong in the category.

Arbitrary inclusion limit

Examples: People over six feet tall, Villages with more than 10,000 inhabitants, Disasters with 5000+ casualties

There is no particular reason for choosing "six" or "10,000" as a cutoff point. A village with 9800 people is not meaningfully different from one with 10100 people. A better way of representing this kind of information is to make an article like "List of villages ordered by size". Note that in our present software, a table can automatically be made sortable by every column.

Not a defining characteristic

Example: People who own cats, Motorcycle riders, Blondes

We should categorize by what is actually important in a person's life, such as their career, origin and major accomplishments. In contrast, someone's tastes in food, favorite holiday destination or amount of tattoos are trivial. Such information may be interesting to put in the article, but is not useful fo categorization. If you could easily leave something out of a biography, it is not a defining characteristic.

Categories by opinion

Example: People who vote republican, People who like ice cream, Politicians who favor legalizing drugs

As above, holding an opinion is not a defining characteristic, and should not be categorized by. Categories such as "Republicans" should be reserved for people doing active work for the party, as oppose to merely voting for it.

Award winners and nominees

Example: Michigan Red Herring Award nominees

While it may be interesting to note all the awards a subject has won in its article, such articles should only be categorized by awards that are exceedingly well-known, such as the Oscar or Nobel Prize. As a rule of thumb, if an award doesn't have an article, it shouldn't have a category either.

Inclusion in a published list

Example: Top-40 songs

Magazines and books regularly publish lists of the "top 30" (or some other number) in any particular field. Such lists tend to be subjective and somewhat arbitrary, and as such don't make for meaningful categorization. Additionally, since there are many of such lists, creating categories for all of them would add needless clutter to all relevant pages.

Actors by film, or films by actor

Example: Starship Troopers actors, or Films with John Travolta

Since most films have several dozen otherwise unrelated actors, and most actors play in several dozen otherwise unrelated films, these categories would add unnecessary clutter to all pages on actors and films. This information is better represented by including a list of actors in the film article, and vice versa.

On the contrary, considering most films have only a single director, and directors tend to have their own style, categorizing films by director is generally useful.