Does colon cancer always make your stools bloody?

Maybe. If having bleeding you should be checked for colon cancer or other problems that can cause bleeding. However you could have colon cancer without any visible signs of bleeding. If you are hi risk, get screened!
Yes. Rectal bleeding is one of the signs of colon cancer, especially if it is in the lower part of the colon. The bleeding is caused by ulceration of the tumor and is usually a later symptom. Early cancers and cancers in the right side of the colon may not show visible bleeding, but may show evidence of chemical bleeding that is detected on stool samples.