Bugs

CodeLayout::ProhibitFatCommaNewline

Avoid newline before "=>" not quoting.

CodeLayout::ProhibitIfIfSameLine

Avoid "} if () {" perhaps meant to be "elsif".

Miscellanea::TextDomainPlaceholders

Check keyword arguments to "__x()", "__nx()", etc.

Modules::ProhibitUseQuotedVersion

Don't quote a version requirement like "use Foo '1.5'"

ValuesAndExpressions::RequireNumericVersion

$VERSION plain number for comparisons and checking.

ValuesAndExpressions::ConstantBeforeLt

Avoid problems with "FOO < 123"

ValuesAndExpressions::NotWithCompare

Avoid problems with "! $x == $y"

ValuesAndExpressions::ProhibitArrayAssignAref

Dubious "@array=[1,2,3]" array/arrayref assignments.

ValuesAndExpressions::ProhibitDuplicateHashKeys

Duplicate literal keys "%h = (xyz=>123, xyz=>456)".

ValuesAndExpressions::ProhibitFiletest_f

Don't use "-f".

ValuesAndExpressions::UnexpandedSpecialLiteral

"__PACKAGE__" etc special words not expanding.

Compatibility

Compatibility::ConstantPragmaHash

Version requirement for hash style multi-constants.

Compatibility::ConstantLeadingUnderscore

Version requirement for constants with leading underscore.

Compatibility::Gtk2Constants

Gtk2 module version requirement for some constants.

Compatibility::PerlMinimumVersionAndWhy

Perl version declared against features used.

Compatibility::PodMinimumVersion

Perl version declared against POD features used.

Compatibility::ProhibitUnixDevNull

Prefer "File::Spec->devnull" over /dev/null.

Efficiency

Documentation::RequireEndBeforeLastPod

Put "__END__" before POD at end of file.

Miscellanea::TextDomainUnused

"Locale::TextDomain" imported but not used.

Modules::ProhibitPOSIXimport

Don't import the whole of "POSIX".

Cosmetic

CodeLayout::RequireTrailingCommaAtNewline

Comma "," at the end of list, if at a newline.

CodeLayout::RequireFinalSemicolon

Semicolon ";" on the last statement of a subroutine or block.

ValuesAndExpressions::ProhibitEmptyCommas

Stray consecutive commas ",,"

ValuesAndExpressions::ProhibitNullStatements

Stray semicolons ";"

ValuesAndExpressions::ProhibitUnknownBackslash

Unknown "\z" etc escapes in strings.

ValuesAndExpressions::ProhibitBarewordDoubleColon

Double-colon barewords "Foo::Bar::"

Modules::ProhibitModuleShebang

No "#!" interpreter line in .pm files.

Documentation

Documentation::ProhibitUnbalancedParens

Unbalanced or mismatched ( ) parens, brackets and braces.

Documentation::ProhibitAdjacentLinks

Put commas or some text between adjacent "L<>" links.

Documentation::ProhibitDuplicateHeadings

Don't duplicate "=head" headings.

Documentation::ProhibitDuplicateSeeAlso

Don't duplicate "L<>" links in SEE ALSO sections.

Documentation::ProhibitBadAproposMarkup

Avoid "C<>" in NAME section, bad for man's "apropos" output.

Documentation::RequireFilenameMarkup

Markup /foo filenames.

Documentation::ProhibitLinkToSelf

Don't "L<>" link to the document itself.

Documentation::ProhibitParagraphEndComma

Don't end paragraph with "," comma.

Documentation::ProhibitParagraphTwoDots

Don't end paragraph with ".." (stray extra dot).

Documentation::ProhibitVerbatimMarkup

Verbatim paragraphs not expanding "C<>" etc markup.

Documentation::RequireFinalCut

Have a "=cut" at end of file.

Documentation::RequireLinkedURLs

Use "L<>" markup on URLs.

Selecting

The restrictive policies are meant as building blocks for a house style. For example "ProhibitBarewordDoubleColon" here, or something like "ProhibitUnlessBlocks". They're usually a matter of personal preference, and "non de gustibus disputandum" as they say in the classics. Trying to follow all such policies would give away big parts of the language and quite likely result in very un-typical code.

Some of the restrictive policies are geared towards beginners. "ProhibitUnknownBackslash" here or "RequireInitializationForLocalVars" are along those lines. There might for instance be good backslashing which the prohibition doesn't recognise, or local variable initializers make no sense for output variables like $!, once you get to the level of knowing to use "local" to preserve such globals.

In general the POD of each policy is supposed to explain the motivation so you can see whether you want it or not. If you're not turning off or drastically customizing at least half of all policies then you're either not trying or you're much too easily lead!