I don't have much experience but I have worked with a researcher in this field and at a private hospital that was doing research in it.
My opinion, ketamine can be a very useful medication but I have serious doubts that many if not most of the ketamine clinics out there are drug dealers with white coats.
Why?
Well first ask yourself why would an anesthesiologist, the one type of physician even want to go into mental health treatment, a field they know so little about with their training?
And to give a medication with no established standard of care, no FDA approval for depression, no professional societal approval, with that medication having a strong abuse potential, all the while charging huge amounts of money for it?
And if even a physician wanted to give it with good intent shouldn't they be giving it only for severe and/or treatment resistant cases of depression? Then why a clinic that is advertising as if they want to give it to anyone even with mild depression and charging huge fees that are above standard treatments for depression?
Again ketamine will have IMHO a place in depression treatment that is more standard and patients can benefit from it now if it's severe enough but to give it out as if it's an SSRI so long as the patient it willing to give money IMHO is bad medicine.
Take for example a specific physician who I will not name who runs a ketamine clinic. His website claims he pioneered a treatment protocol for ketamine. Okay I checked his publications. He has only 1 and it's concerning schizophrenia. He "pioneered" a treatment protocol? Sounds like it's science but if it's not published or at least scrutinized by an outside source this is pretty much home-brewed treatment.
Okay so yes, with any cutting edge treatment one would be practicing outside the norm but ethically such treatments should be limited to cases where the conventional was tried and failed, done under high scrutiny, and not by someone who just read a few journal articles about the topic.
The Green Journal a few months ago published a case of a patient clearly abusing ketamine that was provided by a neurologist. If you read between the lines it seems like this neurologist didn't know WTF he was doing.
http://ajp.psychiatryonline.org/doi/full/10.1176/appi.ajp.2015.15081082
Further buprenorphine is showing emerging data that it too can treat depression extremely quickly. Shall I then start giving it first line to every depressed patient I see? Of course not.
Also a place I used to work at did provide ketamine. It was done as part of a research study and IMHO ethically so especially since it did go through and IRB. All of the borderlines (rich borderlines that is) took it and just wanted to take it again and again and again and when told no they'd freak out and then you had an even bigger problem on your hands---a borderline that wants to use a substance of abuse to treat their emotional dysregulation.