She was anything but a saint. She withheld pain killers from dying patients because she thought suffering was good.

http://all-that-is-interesting.com/mother-teresa-saint

Though Mother Theresa’s medical centers were meant to heal people, patients were subjected to conditions that often made them even sicker. In the same documentary, an Indian journalist compared Mother Teresa’s flagship location for “Missionaries of Charity” to photographs he had seen of Nazi Germany’s Bergen-Belsen concentration camp.
“Workers washed needles under tap water and then reused them. Medicine and other vital items were stored for months on end, expiring and still applied sporadically to patients,” said Hemley Gonzalez, a noted humanitarian worker in Indoa, when describing the Missionaries of Charity location he briefly volunteered at.
“Volunteers with little or no training carried out dangerous work on patients with highly contagious cases of tuberculosis and other life-threatening illnesses. The individuals who operated the charity refused to accept and implement medical equipment and machinery that would have safely automated processes and saved lives.”
It wasn’t just a select few cynical journalists who criticized Mother Teresa’s hospice care, either. In her hospice care centers, Mother Teresa practiced her belief that patients only needed to feel wanted and die at peace with God — not receive proper medical care — and medical experts went after her for it.
In 1994, the British medical journal The Lancet claimed that medicine was scarce in her hospice centers and that patients received nothing close to what they needed to relieve their pain.
Doctors took to calling her locations “homes for the dying,” and such a name was warranted. Mother Teresa’s Calcutta home for the sick had a mortality rate of more than 40 percent. But in her view, this wasn’t a bad thing, as she believed that the suffering of the poor and sick was more of a glory than a burden.
“There is something beautiful in seeing the poor accept their lot, to suffer it like Christ’s Passion,” Mother Teresa said. “The world gains much from their suffering.”
When it came to her own suffering, however, Mother Teresa took a different stance. The ailing altruist received care for her failing heart in a modern American hospital.

The German magazine Stern estimated that only seven percent of the millions of dollars Teresa received was used for charity.