The Pros & Cons (from Someone Who Has Had One)
To me, how useful a sink insert like this ultimately is, will depend on how you prepare meals and whether you are willing to perform a little maintenance. For example, when I was preparing a great deal of fresh produce, it was actually fairly convenient. I’d peel carrots and potatoes directly into the bin and add in fruit cores, etc. and wouldn’t have to open the main trash until I finished cleaning up after the meal.
BUT, and this is a BIG BUT, it only functions properly if you empty it every day. If you forget, especially during warmer months, it becomes a horror film. Like, fruit fly party level. Trust me on this: empty the bin every day.
Not all of them are removable. Based on the images in the Reddit post, this one is removable (the blue rubber liner comes out), which is a huge plus. Those that are non-removable can be difficult to clean and less sanitary.
Why They Feel Obsolete
The primary reason that many people are confused by these today is that kitchen design has changed. With built-in trash cans, under-sink trash cans and composting units, these old inserts feel outdated. Newer houses rarely have them because they take up counter space, disrupt the flow around the sink and they simply look weird unless you have grown accustomed to seeing them.
However, there is a smaller group of people who swear by them, particularly those that compost. You can remove the rubber bin, empty the contents into your yard compost pile and wash it down. Done and done.

What You Can Do If You Hate It
If you’re like the Reddit author and sort of wish it was gone, you’re not alone. One thing I learned the hard way was: do not just seal it shut without determining how it was mounted. Many of these are partially integrated into the counter or sink system, so removing them may create a hole or an unsightly void.
Some people have repurposed them as mini ice containers (for parties), or simply left them shut and used the adjacent area for drying racks. My friend even put a small potted herb in hers and used it as a quirky little herb garden, which was sort of cute.
Well, that solves it. That little rubber bucket with the metal lid next to your sink? It’s a compost bin insert. And although it may seem like some bizarre relic of the past, it was actually a clever little work-around at one time. Ultimately, whether you want to keep it, repurpose it or yank it out will depend on your kitchen practices, but now you won’t be left trying to figure out what extraterrestrial technology fell onto your counter.
Honestly, since I no longer have one, I kind of miss it. Just…not the flies.
It reminds me of another online mystery where someone posted about two odd piles found in her daughter’s room, and just like the sink insert, nobody could agree on what they were looking at until the comments sorted it out.