Oh boy, so opinionated and so wrong at the same time.
You are wrong in so many ways that it is hard to know where to start.
Others have already pointed out the definition of modelling.
If modelling is just to "show of a product" then we would have a distinct lack of art in the world (be that nudes or anything else).
Effectively the model themselves could be classed as a "product" but that is a different argument.
What is a "REAL" client then? Is it the person who pays many thousands (or millions) for a single painting of a bunch of flowers, a person who pays a few hundred for a photograph to go on their wall, a hotel owner who pays many thousands for "artwork" to decorate their premises or an ad agency trying to sell you a bottle of some fizzy drink?
A "REAL" client to me is one who pays for a product or service.
Many of your definition of "REAL" clients do hire models because they are or look "cute" or have good bodies or pretty faces simply because that is what they want. The old saying "sex sells" is still as valid today as it was in the 60's.
Even going by your definition of what a model is, then a model who models nude or even a porn model is still a model as they can and will "instill a pleasant or appealing feeling to the consumer".
Of course there are those around (both in the photography and modelling side) who are less than savoury. Thankfully they are a minority rather than a majority. If you had been around the top echelons of the fashion scene you would know that it is often the clients who are the unsavoury ones rather than the models or photographers.
You say you are familar with the subject in your additional details but I have to say you certainly don't seem to have a clue what you are talking about and are simply expressing your opinion rather than the facts. Although you try and phrase it as if you know what you are talking about.
There are many thousands of models who model nude and would seriously take you to task for saying they are not real models. Many of the worlds top models have and do model nude for a variety of photographers. Photographers who I am sure would like to meet you and explain the difference between what they do and what some guy with a camera does.
You are of course entitled to your opinion, however wrong it may be, but the problem with having an opinion without actually having knowledge of the subject, is that it leaves you open to accusations of "ignorant generalisation" as someone has already said.
You moan about others being rude or judgemental in their comments and yet, in my opinion, your comments are the ones which are extremely rude and judgemental.