I had actually never heard the term Remedial massage, and had to look it up.
Well, first off, Thai massage combines a lot of yogic elements. It is almost a from of partner yoga. There is a great deal of emphasis on stretching and range of motion, in conjunction with more common kneading techniques. One thing that makes Thai massage unique is that much of it is performed from a floor seated posture, as opposed to lying prone or supine on a table. Though very slow paced and relaxing, it could be considered a bit more active in a sense. Yet, as in all massage, the recipient is encouraged not to aid in the movements.
From what I can see of Remedial massage, it appears to combine many techniques of relaxation forms such as Swedish, and energetic techniques such as the Chinese massage, Tui Na. A form such as Tui Na incorporates many elements designed to help correct imbalances in the meridian system, the energetic channels of the body described in Chinese medicine, in which our "chi" or vital energy flows through. It is based on much the same principles as accupuncture.
Yoga works on very similar principles, and a very similar system, manipulating "prana." And this is largely part of the aim of the Thai technique.
Tui Na is also sometimes referred to as Chi Gong massage, as practitioners must engage in many hours of such energy work, in order to strengthen their own chi and develop their healing powers.
I first had this from of massage myself a few weeks ago -- though I have personally practiced Chi Gong intermittently over the years -- and I am truly amazed at the results, even weeks later. Not only did it afford me a great deal of relief from tension, it eradicated edema in my feet that had been plaguing me for months.
As far as the bad experience you describe, you unfortunately got a very unskilled or unattentive practitioner. Though not unhead of, experiences like that are hopefully not very common.
I myself am a certified practitioner of Swedish massage. I can tell you confidently that you should never, ever be sore after a massage, never mind for days afterwards. He was either way to aggresive in his approach, or overly goal-oriented and overworked the tissues. I hope he was informed enough not to apply firm pressure over your kidney region or such. He should have been sensitive to feedback that your body was giving him, though as well, he should have periodically been informing you of the procedures and inquiring as to your comfort. Not enough to disturb your relaxation, but enough to ensure that nothing adverse occurred.
It can be difficult to find a really good therapist, and not everyone pairs well with every therapist, but there are things to look for. Someone with relatively advanced training is always good; and the better the office, likely the more business they have, on top of experience. Two things I would almost insist on, if in the US... One is National Certification. This is a comprehensive wriiten test, required in many states now, proving fairly extensive competency of anatomical knowledge and basic, common technique, as well as professional guidelines and ethics. Secondly is membership in the AMTA (American Massage Therapy Association). This is a professional organization devoted to promoting and maintaining high standards throughout the profession. Two of my own instructors were former presidents of this association. Other than that, it's largely just a matter of finding someone of which you feel comfortable with, can afford, and provides a technique that you find beneficial. Be aware too, that not all therapists have the advanced training necessary for rehabilitation of injuries. Some people are strictly relaxation, and the therapist should know their limits, and stringently adhere solely to what they are trained in.