- Opaque, confusing, vague or misleading
- Garish, over the top or ugly
- Ironically reminiscent of older design trends that were embraced in earnest at the time
In video games, "retro"/pixel art styles are wildly popular, sometimes because story and gameplay are more important to the creators, sometimes because it was seen as a nearly lost art.
In web design, there have been several recent waves of "retro" trends embracing the styles once found on Geocities/Angelfire or even the original Myspace. There have also been several variants of "brutalist" design with oversized and unusually placed design elements, clashing or exceedingly drab colors. Such brutalist design has been embraced even by mainstream sites like Bloomberg, and in a lot of ways the novelty has worn off and it's just part of a resurgence of design diversity across the web after a long period of uniformity.
In other GUI software, intensely oversaturated colors (like those found in iOS since its "flat" redesign) were mocked mercilessly when introduced but seem to have almost become commonplace.
Like anti-humor, anti-aesthetic is sort of an oxymoron (as TFA points out). It turns out a lot of things that seem like they would be unappealing are actually quite appealing to at least a subset of the population. I am quite fond of a lot of "brutalist" design and find intensely oversaturated colors (in balance) pleasing to look at.