Flats made from recycled plastic bottles hardly sound like a formula for a bona fide fashion phenomenon.But since Rothy’s launched in 2016, the direct-order accessories brand has won over celebrities — including Meghan Markle, Jennifer Lawrence, and Katie Holmes — and commuters alike, who swear by its shoes for everyday comfort.I’ve even spotted Rothy’s shoes on the feet of many women in our newsroom; they’re easily identified by their signature blue streak around the heel. It seems the main appeal is a mix of comfort and style that’s made better by being machine-washable. It’s all enticing enough to create true fans out of people who keep coming back for more despite not really caring about fashion.At least that’s what made writer Shaena Montanari a Rothy’s superfan. “I was more looking for something with function and comfort,” said Shaena, who’s owned over 20 pairs of Rothy’s over the past 10 years. “The features won me over.”Given the fanfare, we had to know firsthand: Are Rothy’s really the Goldilocks of comfy yet stylish shoes, or do its flats fall, well, flat? Ruthie Darling/NYT WirecutterOver the last 14 years, the brand has expanded well beyond ballet flats, to block heels, handbags, and even sneakers. But a Rothy’s rep confirmed that only four styles make up its core collection, which is available year-round. The mainstays are The Point II, a classic pointy-toe ballet flat, available in two widths; The Square Mary Jane, a trend-forward flat with a stretchy strap; The Penny Loafer, a classic slip-on shoe with a padded heel; and The Casual Clog, a slipper-like minimalist flat.All four of these styles are made of Rothy’s signature knit, a recycled-plastic yarn that’s made from water bottles. (The company also makes items with other materials, like merino wool and hemp, but we stuck to its signature for the sake of testing.) This knit, which feels like a thicker mesh, is meant to have zero points of irritation and to give the shoe flexibility, so as to reduce or eliminate the break-in period, said Caroline Swierszczyk, Rothy’s design director of women’s footwear.Over about two weeks, a panel of four testers wore these shoes everywhere, including to work from home, take six-hour flights, run errands, and go to the office. We tested each style for comfort and wearability, as well as their machine-washable features. We also focused on style value in an effort to understand why so many people swear by these shoes for everything from TSA lines to corporate offices.Our findings were split. We’d be happy to spend money on some styles, but for others we found the drawbacks outweighed the promise of blister-free comfort. Here’s what we recommend and what we’d skip.