The phrase "can't cut the mustard" purportedly stems from the idea that mustard is something that adds real flavor or zest to life (the "cutting" refers to the harvesting of the plant). Indeed, mustard yellow is a high risk/high reward color. It can look dated and fusty (think old mustard colored appliances). But it can also look rich, spicy and smoky, especially when paired with grays, blues and even dark red.
FIRST ROW
1. Myrica Stylist
2. Hammers and High Heels.
3. Guardian
4. Stylist Abigail Ahern's home in London via 79 Ideas.
5. Look! Chocolate Brown and Mustard Yellow
SECOND ROW
6. Charles Mellersh's home in London on Remodelista
7. Jessica's Mid-Century Style Room
8. Lisa's Black White & Cool Room
Images: As credited above.
Small Cool Lessons: Discovering Small Space Design Ideas That Really Work
Beatriz's Fun & Functional Workspace
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Sheex Bedding
How to Make Easy 3-Ingredient Energy Bars at Home
How to Make Fresh Pasta Dough in the Food Processor
Oooh...I thought it would be easy picking a fave, but nope. I love em all!
That is the second mustard floor at Apt Therapy this week. Is it a thing, now?
Whatever - I looove them both.
I love everyone of these!!! rEally awesome!!!
This reminds me: was the yellow/black/white Room For Color entry that was speculated as being fake (created in a store or studio) found to be so? I get a 404 error when I try to go back to it. If so, that's hysterical/nutty.
Whaddya mean dated and fusty? Mustard is just plain fabulous, and I also love all these.
Mustard looks terrible with most skin tones, at least for fashion. It might be edgy for interiors, but I find it unpleasant. YMMV
By the way, mustard has a faintly greenish cast. I'd say number two above is gold -- a warmer and more livable color...
Love them all... Really high impact for something as small as even a throw.
(the "cutting" refers to the harvesting of the plant)
... is that what it means? That makes zero sense in context. Shouldn't it just mean that you can't omit it from the recipe?
i thought it was can't cut the "muster." as in the opposite of "pass muster" (to be acceptable / pass inspection).
but i could just be thinking of can't pass muster, and cut the mustard is just a similarly sounding phrase of completely different origin
On googling, pizzapi seems to not be entirely incorrect, whereas the meaning of the idiom as given in this article is, if not totally wrong, then not the predominant usage. Someone who "can't cut the mustard" is incompetent.
As for the article itself, most of the examples just look yellow to me.