Enzyme, please continue with your thoughts. I'll give you a direction and you can help us out. Sodium lauryl (or laureth) sulfate is the number one ingredient in most shampoos. It is also about the only ingredient in bubble bath. I'm going out on a limb here but I'm thinking that SLS is a foaming agent. Am I right?
J&J Baby shampoo does not have any of that in it. Could you please comment on the ability of the baby shampoo and conventional shampoo ingredients to strip oils and/or dirt out of hair, AND THEN (to bring this back to the topic) would you please comment on the use of baby shampoo versus bubble bath as a surfactant for gardening use. If you think I'm too far off topic, please email me.
Sodium lauryl sulfate has some sudsing activity along with detergent activity (some compounds clean, some suds, some do both, some repress suds). For those that don't know, sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES) are not the same compound, although both are sodium salts. I also would not bank that an ingredient list tells all of what is in a product. We've become so accustomed (brainwashed?) to thinking that it isn't working if it isn't sudsing that it's easy to waste/overuse non-sudsing products. As to whether sudsing and non-sudsing products clean comparably, they probably do under average conditions. I think it's safe to say that there are two types of non-suds/low suds compounds. One class doesn't generate much sudsing, and the other generates suds but uses bubble repressers to break up the suds.
As for the baby shampoos, I haven't tried them to see how far they will go to strip serious oil and dirt. I seriously doubt that baby hair presents the type of cleaning challenge that a construction worker might present. My guess is that baby shampoo "conditions" more than it cleans. Being that hair primarily is a cosmetic issue for most people, most probably judge "clean" by feel, appearance, and aroma, all of which can be manipulated. I don't know how many different baby shampoos J&J makes, but the No More Tears product pretty much is water, detergent, polyethylene glycol compounds (PEG-80, which acts as a surfactant, and PEG-150 compounds), a quaternary ammonium compound (recall the discussion about wood preservatives), conditioner, fragrance, preservative, and synthetic dyes. About the only time I would use it is if I were bathing an animal and I had to clean near its eyes. I would prefer not to use it on a child, and I surely wouldn't buy it to use in the garden; I want to know if I'm getting something like that in my eyes, so I don't have much use for a tearless shampoo.
As for using a non-sudsing detergent vs a sudsing detergent/soap in a horticulture setting, I suppost it would depend a little on what the situation is. If the need is purely for a surfactant, then suds tend toward the wrong direction. If one is using it as an insecticide, then the suds probably help via suffocation. If one needs a marker to gauge where/how heavy the coverage is, the suds could help there. Solution pH, water hardness, and maybe even equipment maintenance could enter into the product selection process, and the makeup of the solution (if it is more than mere soapy water) could affect the choice. At the application level and with the concentration that a gardener is likely to use, it might be hard to tell the difference. In terms of the product's life cycle and what it takes to produce it, I think there's quite a bit of difference. If I can't get by with grey washwater (i.e., an additional use rather than a waste) in the garden applications, I prefer KHWOZ's domain of soaps, never mind the suds. I wouldn't say that my life is free of SLS or SLES, but after seeing how they and their stronger cousin SDS interact with skin tissue in the lab, I'd rather do without them. One commercial line I like is the Aubrey product line. There is quite a bit to the surfactant/detergent field, and there's a lot on the Web about. If I haven't answered your question or if the answer put you to sleep, ask again.