The main causes of thin stools and unclean bowel movements include intestinal tumors, perianal abscesses, hemorrhoids and improper diet. 1. Intestinal tumors: people with intestinal tumors will have changes in the form of defecation, which will be thin and soft and not clean. 2. Perianal abscess: people suffering from perianal abscess will also have unclean bowel movement because of the pain, and perianal abscess can also lead to thin stools. 3. Hemorrhoids: when hemorrhoids attack, because of the pain will not dare to defecate, the discharge of the stool is more soft and thin, always feel unclean. 4. Improper diet: when eating unclean, greasy and spicy food, the gastrointestinal tract is stimulated, can also appear in the stool is more soft, not clean symptoms. There are many other causes of thin stools and unclean bowel movements, and it is recommended that you consult a doctor in a timely manner to clarify the cause of the problem under the guidance of a professional physician.