Nah, it's not their vocabulary per se that tips me off, the words are not particularly weird. Look at their profile. They respond to every post with the same kind of cheery demeanor, saying 'wow, that's really interesting, [basically repeats the thought and gives vague overly sincere value judgement]'

They don't reply to comments, they are only active in two subs, they don't change their tone when being called bots. I am 95 percent certain they are not human, but one of a couple of bots that have been in this sub a lot, some more convincing than others