The founder of Arya Samaj, Maharishi Dayanand Saraswati has enjoyed huge popularity until recently when his false personality and poor knowledge of the Vedas was exposed by Sant Rampal Ji. Maharishi Dayanand Saraswati was considered a knower of the Vedas. He actually translated Yajurveda and a part of Rig Veda before he died in 1883. Before he translated the Yajruved, he wrote a book called Satyarth Prakash which contains his own views about God and is completely opposite to the knowledge given in the Vedas. This was recently brought about in the open by Satguru Rampal Ji when he showed the faults in the knowledge given by Dayanand Saraswati and showed it on national television. An account of that documentary / debate is shown in the video below.
Moreover various biographies of Dayanand Saraswati show that he had scores of vices and was addicted to bhang, used to smoke tobacco, take sniff and thus does not deserve the title of a social reformer. He was also absconding at the time of mutiny of 1857 and has until now enjoyed a false reputation of being a freedom fighter. The last nail in the coffin is the chapter 4 of Satyarth Prakash where he has given shameful and disgusting account of his own views about widow marriage, extra-marital sex, husband and wife relationships and much more. His views promote prostitution and illicit sex. Throughout his book Satyarth Prakash he has made unacceptable commentaries on great saints like Kabir Sahib, Guru Nanak Dev Ji, many Hindu mythological stories, Islam and Christianity. He truly deserves the title of "a lecher", "a wretched man" and he definitely was not a Maharishi.