The GCC state “There is some evidence, though more research is needed, that you may see an improvement in some types of:
• asthma
• headaches, including migraine; and
• infant colic”
The problem is not with claims, it‘s with the language. There’s no evidence for cure but if improvement means symptoms generally declining, which I’d say is an improvement in anyone’s book, then there is, if improvement means complete resolution then there isn’t. Language, you see?

There is evidence that chiropractic can help, and I freely admit it is not strong and pretty hard to defend against pedants, but it is not a complete disaster and certainly not in the realms of bogus, particularly if improvement is an acceptable goal. See:

Chiropractic care for nonmusculoskeletal conditions: A systematic review with implications for whole systems research
Hawk C et al. May 2008.
The Journal of Alternative and Complimentary Medicine 2007; 13(5): 491-512. Chiropractic Guidelines and Practice Parameters (CCGPP) expert committee.
This was a comprehensive literature search (using PubMed, Ovid, Mantis, ICL, CINAHL) which identified studies evaluating spinal manipulation and/or mobilization (both chiropractic and osteopathic) or general chiropractic management of NMSK conditions.
The aims of this study were to:
• evaluate the efficacy of chiropractic “care”, not meaning only spinal manipulation, on NMSK conditions and,
• identify specific deficiencies in the literature in order to develop a whole systems approach to researching this topic.

The bit covering asthma, in summary, is:

“Asthma (15 citations total):
3 RCTs reported no adverse effects from spinal manipulative therapy (SMT) although physiological measures did not improve in any study, medication use generally declined, and symptoms were generally reported to improve.”

Now, at:
http://www.bio-medicine.org/medicine-news/The-Adverse-Effects-Of-Asthma-Medication-2935-1/
it states that:

“Latest research shows that a common class of drugs used for acute asthma attacks might be causing the very thing it aims to treat. Many people with asthma rely heavily on these medications, sometimes taking them several times a day.”

So what would you do if it was you who was suffering with asthma – give it a go and see if it led to “medication use generally declined, and symptoms were generally reported to improve” or press on with the drugs?

I know what I would do and I’d be right chuffed if things improved.
Language, do you see?