Ass to mouth seems to be a craze nowdays, it's become a common scene in a lot of porn.

The main issue to be concerned with is the vast amount of bacteria that is present in the anus, even after a thorough flushing and cleansing. Taking some of these bugs back into your body orally could cause problems if you have an unknown issue going on down below.

Another issue is the cleansing process itself. You would necessarily remove many of the bacteria from your system during this cleansing. Your body has them there for a reason, they are a necessary and important part of how your body works. Removing them frequently could cause lower bowel problems if it's done often enough. I don't know how often would be too much, but it's something to keep in mind.

I've heard commentators state that a couple of times a month won't cause an issue, whereas every day would, but they would not commit to a safe number between those two because everybodies body is different and how their systems would tolerate this are different as well.

From what I have read and heard about this, if you are healthy, take basic precautions, and don't over-do it there should not be any lasting or delayed issues to worry about.