While its not a Pokemon that I'm fond of, I think people have over-exaggated really Garbodor. You'd think the end times were on us. I'd say Garbodor just looks more or less like a drawing of a swamp creature. There are pokemon who I dislike the design and concept of more from Mr. Mime to Probopass to the Ultrabeasts. There are certainly also less competent pokemon than Garbodor by no accounts is Garbador a bad Pokemon to use like Wormadam or Unown.
I think if this same Pokemon had just been called a gremlin or mud bunny it would not be nearly as controversial. Pokemon based on more abstract ideas and objects always divide fans. In this case Garbardor's not even the "cool" object that is okay to like such as say Aegislash. an enchanted sword. Instead Garbodor is based on a pile of garbage. People look to Pokemon for a world full of wonder, where creatures are beautiful, cool, mighty and even just plain cute. Whereas Garbodor is the harsh real word staring back at you. Its not pretty and its not meant to be, but people don't want that.
I have to be honest that I'm not even ready for this idea myself of the garbage pokemon, but I understand why GF made this pokemon and you have to give them credit for putting some thought into why its like this. Muk, Weeezing and Garbodor are intended to form a trinity each representing the pollution ravinging the sea, air and land. Dobbs had a good video about this on YouTube. At the end of the day I think Garbordor does make sense.