I don't hate Trubbish, only the Vanillite line.
I never really like food/object pokemon, but if it got a design that make it look more than just an object with eyeballs its okay.
Like geodude's arms which make it look like a human, or Swirlix which remind me a dog.
But the Vanillite alaways was... an ice cream with eyeballs, which was really stupied...
I think something a lot of people overlook is the fact that humans tend to connect more with things that they can give human characteristics to. This is exemplified very well in the above post. I was watching a video by the YouTuber "Tamashii Hiroka" and she explained this quite well. The above statement is a lot of the reason why, as a general statement, humans get closer to certain mammal companions that they see as "like them." Now, as a civilized species, we've gotten to the point where we can always overcome these stereotypes and such, and we can get attached to pet fish.
More often than not, though, one would get closer to a dog- a mammal that shows more emotion, more "humanity" than a scaly, underwater, somewhat-derpy looking creature like a fish. This goes for Pokemon, too. Sure, there are plenty of fish Pokemon that people like. So, my last point seems kind of dumb, right?
But here's what I mean. Take the Pokemon Basculin. Its eyes are drawn to be expressive. It looks sort of angry, you could say. While Trubbish also looks to be slightly expressive, it seems more dull than not, and isn't really an animal. Automatically, many people equate it to an object and thus can't find themselves liking it or becoming attached to it. Again, not all people are like this, but many of the haters seem to display this behavior. Of course, their stats and move pools can be a factor- but I'm talking more about the people going after the design-oriented hate. With the Vanilish line, well, they're food. Most people I know don't like to think of something that we consume for dessert as a monster that can be battled with. Sure, we eat cows like Miltank, and fish like Magikarp, but those start out as living animals where as ice cream is a product of human development. The day that I try and fight a bowl of ice cream is not a day that'll be coming anytime soon.
Nostalgia plays a role here too. Most people I personally know automatically hate on newer Pokemon, because that's just the trend. They take what they like from the old days, remember the good stuff, and then they continue on grumbling about how GameFreak is "running out of ideas." While that is a valid opinion, it's an opinion that I cannot respect due to the fact that I believe it to be very ignorant. Every generation has its bad Pokemon. Muk and Grimer are living piles of sludge. Sludge, for those who don't know the technical definition, can be defined multiple ways. Here are some of them.
"1. Semisolid material such as the type precipitated by sewage treatment.
2. Mud, mire, or ooze covering the ground or forming a deposit, as on a riverbed.
3. Finely broken or half-formed ice on a body of water, especially the sea."
Essentially, Muk and Grimer are sentient piles of poop, or mud. And mud? Comes from dead plant and animal matter. Really, they're not exactly the most "creative" if you're going for that. They're just waste and dead stuff. Because they're obviously not made of ice like the third definition there. I like Muk and Grimer, personally, but for the sake of this big ranty statement here, I'm using them as an example.
Now, none of what I said up here is meant to offend anyone, nor is it meant to fully dismiss any opinions, but to give my take on this whole situation. Sorry for the eyeball burning rant everyone. I also don't intend to generalize as much as it seems, I'm well aware that people can have many varied reasons for liking/disliking certain Pokemon beyond these reasons.