How bad are the bad trips? And how often they appear?
The experiences are ineffable and unlike anything perceived by prior physical sense. The integrative aspect - taking the ecstatic vision and letting it into daily life - is an ongoing process which often takes up to a year. And so good or bad is too simplistic a lens in which to judge the psychedelic experience.
Moments of sheer terror, perceiving the blackest of black, are common. So too are moments of pure bliss and the sensation of limitless loving grace. These become trivialized by the overall experience, which is powerful enough to fully reorient a person's understanding of what it means to be a human being.
The result depends heavily on the pre-existing mental framework that engages with the medicine. For example, people from traditional western religious backgrounds may manifest demons, angels, and heaven and hell within their experiences -- if that is what _they feel they need to experience_ in order to realize the intention that they have brought with them into the ceremony.
My personal view revolves around the entrenchment of an individual's ego. Those who meditate and who have comfort with nondualistic thinking tend to ride the wave better than those who have very rigid conceptions of their self identity and its resultant patterning.
A rewarding read was the academic 'Antipodes of the Mind', a phenomenological study from cognitive scientist Benny Shannon. It is the most rigourous resource that addresses the wondrous weirdness of the Ayahuasca experience.
However, there have been very nasty experiences that have happened as a result of not following the very strict guidelines of pre and post ceremony care. It is recommended that you abstain from alcohol, sugar, sexual conduct for varying time periods. It is also required that all medication - within reason and with a long list of disallowed contraindications - be weened off of prior to partaking.
The medicine is serious stuff. It is beautiful stuff. And it should be approached with great care. If you take it with a reputable group, prepare appropriately, and follow the post-ceremony guidelines, there is a high likely hood of a net positive experience. If you do not, well...
Once back, it can easily take a year to unpack the experience, and find the right metaphors to attempt to, almost, but not quite really, slightly describe an infinitesimal part of the experience, maybe. :)
In metaphor, each person keeps their affliction locked within a box. And each person must be the one to create their own key. A person must be willing to open this dark box and release whatever is in it -- the sexual abuse, the long lived depression, or the significant trauma --- and _decide_ to become healthy.
An intention is saying: "This is what I have locked in my box. I want to get rid of it. I want to get better."
Real examples are:
* I no longer want to be depressed.
* I want to get over past sexual, emotional, or physical abuses.
* I want to become sober.
Through the ritualistic component of the ceremony, individuals then go deep within themselves to find and create the narrative, the key, to open the box. The contents of the journey will be unique to each individual. For some, it is getting out of hell or exorcizing a demon within themselves. For others, it is going back to their younger selves to give them love, strength, and support to get over what almost destroyed them. Or, perhaps just catch a glimpse into the delightful madness that is beyond self.
Of course, there's no way of doing a direct comparison, but curious if you have a feel or opinion on it, or might know of anyone who writes on that topic.
It's not even a bad trip necessarily, a positive trip can still cause after affects, increased risk of psychotic episodes, or pretty severe anxiety and it's very hard to predict whether or not you'll be unlucky.
Then again, I think your question comes down to semantics. I have heard friends say a bad trip is their best trip. But anyways and above all, I want to say, don't use labels of good, bad, etc, and just experience the experience.