Whether or not a**l sex is bad is a matter of opinion. Some people love it, some like it, some think it's just ok, some tolerate it, some dislike it...you get the idea.
Some people have a**l sex every day, yet their stuff isn't just all falling out as they walk down the street.
Here are some things that might help you out.
"a**l sex, just like any other type of intercourse, is a preference of the partners that choose to engage in it. There is no single answer that I could give which would generalize why women enjoy a**l sex. However, the a**s have nerve endings which are interconnected with the main pelvic muscles. The outer portion of the rectum, like the v****a, has several nerve endings while the inner portion responds mostly to pressure. Sexually it is the closest erogenous neighbor of the genitals. Liberal use of some type of lubricant is critical, as is slow penetration of the a**s, allowing tissues to stretch and the muscles to relax slowly. Great pain can be experienced if partners do not take time to wait for the muscles to relax. It is also important to use a condom to prevent any sexually transmitted infections between partners; indeed, fecal material can get on the p***s if it is present in the lower colon. Some problems are possible: micro tears in the wall of the rectum after a**l intercourse is common. Tenderness and soreness are typical and can affect regular bowel movement. Penetration can actually act as "peristalsis", the regular movement of the intestine that leads to a bowel movement, so the penetrated partner may have an urge to defecate, especially if there is feces in the lower colon. Ejaculation inside the rectum is not harmful. Partners should always be equally willing to engage in a**l intercourse, especially due to the tendency of the muscles to contract and tighten when nervous."
http://studenthealth.oregonstate.edu/answerspot/message.php?message=26http://www.gaiaonline.com/guilds/viewtopic.php?t=893007http://www.thebody.com/sowadsky/answers/quest554.html