They will wear plaid and stripes together. They'll wear white after labor day. They'll wear neon green with orange.

And the worst part of it is... they do it intentionally.

These are the characters who really don't care if they have a Limited Wardrobe or an Unlimited Wardrobe, they'll dress like a Rummage Sale Reject either way.

Please note, this is when their lack of fashion sense is noted In-Universe. This is not when the fandom or the viewers disagree with the character's fashion choice.

There are two types of this.

Oblivious To Fashion

The character is completely oblivious to the rules of fashion, and could not dress themselves without the assistance of a patient fashionista, a tailor, and a doorstopper of a "How To" guide.

Ignores Fashion

This character does know the rules of fashion, but intentionally ignores it all, either to spite the status quo as a form of rebellion, or as a form of asserting their individuality.

Will probably involve Impossibly Tacky Clothes. See also, Tacky Tuxedo.

Examples:

• In Animorphs, Cassie is noted (mainly by Rachel, the series' fashionista) to have a complete lack of fashion sense. Throughout the series, Cassie's usually wears overalls covered in bird poop, and ratty jeans. Rachel tries to remedy this all through the books, to no avail. It should be noted though, that Cassie could give a damn, as she's usually too busy saving injured animals to give even the slightest thought to how she looks. Hence, she's Oblivious To Fashion AND Ignores Fashion at the same time.
• Pip, from Sequential Art, as evidenced here.
• The girls from Sleepover think that Julie's mom has none, as evidenced by their disdain for her fashion choices from The Eighties.
• Sheldon Cooper from The Big Bang Theory, when dressing formal, favors checkered suits or leisure suits in loud colors. When Penny suggests a more traditional suit, he complains that it's too monochromatic.
• In Garfield, Jon Arbuckle is sometimes shown wearing goofy and unstylish clothing. This is usually remarked upon by the other characters.
  Garfield: Some people wear clip-on ties. Jon wears clip-on suits.
• Italian TV program Ma come ti vesti? (which roughly translates to "What on earth are you wearing?") features two fashion experts who give tips to people with extremely poor fashion sense.
• Daria is definitely an Ignores Fashion; she knows what fashion dictates but chooses to dress differently to assert her individuality and annoy Quinn.
• What Not To Wear is basically made of Oblivious To Fashion but with Ignores Fashion's thrown in sometimes as well. At least until the "how-to" gets done and they're made over.
• The Egyptian mummy named Harold in the 1997 movie "Under Wraps." The kids who bring him to life hide him underneath tacky 1970's duds and sunglasses, in a montage playing "Get Down Tonight" by KC and the Sunshine Band.
• FromTitanic, Jack fits the bill pretty well. Justified, as Jack is poor, and doesn't have any extra clothes to start with.
  Molly Brown: What are you planning to wear? (Jack looks down at his clothes. Back up at her.) I figured.