Open a few good books and essays, and see if there are adverbs, "very", passive voices, or other bad forms. These are reputable works written by careful and capable writers, and enjoyed by many readers. If they are all deemed wrong in the eyes of such advice, it's the advice that's wrong.
The valuable lesson is to actively think about the words you use, whether the text accurately convey what you mean, in the tone you desire, and is readable by your intended audience.
I'd say a good pair of thesaurus and dictionary is much better than this website. At least you got multiple candidates, an explanation of each, and get to choose the most appropriate one.