Not quite. What you find in water soluble degreasers are surfactants, not emulsifiers. A surfactant is a compound that acts to modify the polarity of a polar solvent (water) so that a nonpolar compound (grease and oil) can dissolve in a portion of it. It works by forming micelles which have a nonpolar core with a polar shell. Take a look at the link to see what it looks like.

An emulsifier is a compound that stabilizes an emulsion so that it doesn't break apart into two layers. Think mayonnaise or "green" mineral spirits.

I applaud your correct usage of "organic" as it applies to organic chemicals. Unfortunately most people won't understand. "Organic" has come to mean "natural". Most people would call the "green" cleaners "organic"...they would be wrong but they've kind of won that battle.

A couple of other corrections: First most alcohols that people are going to be able to readily obtain...methanol, ethanol and isopropy alcohol (2-propanol)...are not just soluble in water to "some degree". They, as well as acetone, are infinitely soluble in water. They are polar enough that there is no mixture of those compounds that will phase separate with water. But that polarity is what makes them poor choices for grease cleaners since grease is only slightly or totally insoluble in alcohols and acetone.

WD40 is much more than "basically mineral spirits". WD40 is about 25% mineral oil which is added for lubrication purposes. Adding oil to a "degreaser" defeats the "degreaser" part. WD40 has its uses but using it as a cleaner isn't necessarily one of them.

Sorry but this is a common mistake. Rags that are soaked in bicycle lubricants don't spontaneously ignite. Oils that spontaneously ignite are curing oils like linseed oil or tung oil. Those oils have a chemical functionality in them that undergoes chemical reactions to harden or, more correctly, polymerize. The chemical reaction produces heat which, when confined in a wadded rag can reach a high enough temperature to ignite the rage.

The oils and lubricants used for bicycles aren't that kind of oil. They lack the chemical functionality to undergo hardening. That's probably a good thing since you don't usually want a hard protective layer on parts that need to move.

Most all of the spray degreasers that you are going to use on a bicycle are going to be of the same general type. They are surfactants in a water base. Think "Formula 409" but with a bit more punch. They work well enough for surface cleaning like gunk on the frame or even on the larger parts like chainwheels and derailers.

But if you need to do deeper cleaning or need to clean inside a chain, something like mineral spirits does a better job. It's more effect because you can use less of it and still clean more with it. I wouldn't put it in a spray bottle and spray it...making air/fuel mixtures isn't a good idea...but you can soak a chain in a (very) small bottle of mineral spirits and get more oil and dirt out of the chain than gallons of water based degreasers.

And cleanup is much easier. With a water based degreaser, you need to remove the degreaser with water, then you should remove the water with something so that it doesn't sit there and rust the chain. There are several steps to properly cleaning a chain with water based cleaners. And, generally, you can't reuse the water based degreaser after a cleaning.

A chain can be agitated in about a half cup of mineral spirits, fished out and allowed to evaporate. That half cup of mineral spirits can even be reused for several chains before it's got too much oil and not enough mineral spirits to clean adequately.