Reading the answer from @HallsofJustice, the report from Gaudiano & Herbert JD (2000) was a Skeptical Inquirer report, and as the name suggests, their reports contain the extreme end of skepticism.
For most of its existence, the Skeptical Inquirer (SI) was published by the Committee for the Scientific Investigation of Claims of the Paranormal, widely known by its acronym CSICOP. In 2006 the CSICOP Executive Council shortened CSICOP's name to the Committee for Skeptical Inquiry (CSI) and broadened its mission statement (Wikipedia).
Whilst I concede that there are elements of Jungian theory which can be questionable, I am a defender of psychological theories developed by Freud and others. Yet, some of these theories are considered pseudoscientific and I am skeptical of reports by the Skeptical Inquirer on the basis that I wonder if they ever produce unbiased reports. I wonder how 90% of psychology would stand against their "scrutiny".
Without reading more works of Gary M. Bakker I realize that I cannot fully comment on what he writes but it seems intriguing when he is someone who
has published in both clinical (Practical CBT) and skeptical (God: A Psychological Assessment) fields (Skeptical Inquirer).
It is a bit of an oxymoron when your work involves "scientifically studying" a psychological theory or concept on one hand, and writing about God as though He exists when in the scientific realm, He cannot be considered to exist.
Reading Bakker's 2013 paper cited in the answer by @HallsofJustice you get a feeling that the paper is going to be totally biased against EFT right from the start.
Reviewing one paper on the subject, Bekker reports that EFT slightly outperformed diaphragmatic breathing (Wells et al., 2003, p. 958).
They suggested (p. 961) that the EFT effect is unlikely to have been a placebo effect because, in their experience “many people are initially skeptical” about EFT.
Reviewing another 2 papers:
two EFT studies were unpublished small “partial replications” of the Wells et al. (2003) study (Baker & Siegel, 2005; Salas, 2001). Baker and Siegel (2005) used a “supportive interview” control instead of diaphragmatic breathing, and again EFT performed better on subjective measures but not on heart rate change or on follow-up.
Bekker went on to state that "despite such sparse and methodologically weak evidence", Feinstein (2008) concluded that the Wells et al. (2003) study helped to bring energy psychology past the threshold formulated by Division 12 Task Force of the American Psychological Association, establishing EFT as a probably efficacious treatment for specific phobias (page 210).
Bekker concluded that EFT along with Energy Psychology should be considered pseudoscientific as it is in the same vain as faith healing etc.
When you look at the whole picture, Gary Craig’s EFT (Craig & Fowlie, 1995) does not just involve tapping and the basic idea is given in his website along with a free copy of the theory behind it in PDF format and for Kindle. EFT uses positive affirmations to counteract negative thinking patterns.
When you combine this with Sebastian & Nelms (2017) you mentioned in the comments along with Wells et al. (2003) plus Baker & Siegel (2005) and Salas, (2001). There is strong evidence to suggest EFT is effective.
As I pointed out in a meta post here and in my blog article on pseudoscience in psychology, which expands on the meta post, just because the effects cannot be scientifically measured, it doesn't necessarily mean that it is not effective when patients are consistently reporting significant benefits.
Bakker, G. (2013). The current status of energy psychology: Extraordinary claims with less than ordinary evidence. Clinical Psychologist, 17(3), 91-99. doi: 10.1111/cp.12020
Craig, G., & Fowlie, A. (1995). Emotional freedom techniques: The manual (with video and audio tapes). Sea Ranch, CA: Author.
Feinstein, D. (2008). Energy psychology: A review of the preliminary evidence. Psychotherapy: Theory, Research, Practice, Training, 45(2), 199–213. doi: 10.1037/0033-322.214.171.124
Gaudiano B.A., & Herbert J. D. (2000). Can we really tap our problems away?. Skeptical Inquirer. 24(4). Retrieved from: https://skepticalinquirer.org/2000/07/can_we_really_tap_our_problems_away/
Salas, M. M. (2001). The effect of an energy psychology intervention (EFT) versus diaphragmatic breathing on specific phobias. Unpublished master’s thesis. Kingsville: Texas A & M University.
Sebastian, B., & Nelms, J. (2017). The effectiveness of Emotional Freedom Techniques in the treatment of posttraumatic stress disorder: A meta-analysis. Explore, 13(1), 16-25. doi: 10.1016/j.explore.2016.10.001 pubmed: 27889444
Wells, S., Polglase, K., Andrews, H. B., Carrington, P., & Baker, A. H. (2003). Evaluation of a meridian-based intervention, Emotional Freedom Techniques (EFT), for reducing specific phobias of small animals. Journal of Clinical Psychology, 59(9), 943–966. doi: 10.1002/jclp.10189.