Quote from the Shtefanesht Rebbe, R’ Menachem Friedman (son of Ruzhiner Rebbe): “Personally I do not know at all what is the meaning of the word frum also my father did not mention such a word to me. But it appears to me that it is a type of garment whose outward cover is pride, whose lining is anger, and which is sewn with the black of depression.” (The House of Rizhin, by R. Menachem Brayer)
I believe that instead of judging people by their label (whether it’s imposed on them by someone else or self-chosen), look at their actions and beliefs instead. There is less of a difference in the different people who call themselves chareidi or yeshivish than there is in the words Modern Orthodox, which mean different things to different people. To quote Rav Schwab (when asked a question in which someone who was embezzling money was referred to as a frum yid), “If he is embezzling from the government, he is not a frum Yid!”
Even if someone claims they don’t keep whatever aspect of halacha because they’re “Modern Orthodox,” that no more implicates other Modern Orthodox people who don’t feel the same way as he than that “frum yid” who was an embezzler represents all shomer torah yidden.