>>283691365
Slop is food waste fed to pigs. It might be vegetables left too long in the fridge. It might be that banana you refused to eat because it was brown, but also refused to throw away because it was still edible, until it turned black and fuzzy. It might be literal shit (google pig toilet). It might also be that last bite of bacon (let's just ignore the cannibalism aspect of this analogy since I have no idea what pigs actually would prefer to eat) you just can't finish. Sometimes relatively good stuff ends up in slop. It's not good enough for human consumption anymore, but it's more than good enough for pigs.
When someone says a certain anime slop is good, they are admitting they are a pig and will consume anything. But some things are better than others, even to a pig. We might be consuming waste here, but every once in awhile we find a piece of bacon among the moldy vegetables. And if a slop is really good, it might be all half-gnawed pieces of bacon, so to speak. Still not fit for human consumption, but very good by a pig's standards.
>>283692052
I didn't watch it because the guy was too ugly, but slop isn't about what's good. It's about what's bad. Slop is slop because the producers didn't think you would care they slipped that rotten banana in there because they knew you were a pig.