What happens to the money if...?

When you hire any of these companies to represent you, and you are in a payment plan,
that is comprised of the estimations on past "performance standard" based on the average negotiated amount that the Company(ies) have calculated the amount of the debt anywhere form 40% to 60%, sometimes claims of 75%.
What happens with the money that the client pays every month when the "negotiators"
have been able to dismiss the debt, using the F.D.C.P.A rules?
Does the company give back the money?
How do we know that the companies will even tell the clients that the debt was dismissed
using legal methods to dismiss debt, such as "Debt Validation"?
The "negotiation" companies usually say the they will "cover the difference".
Aren't they just using the client's own money, from the debts that were dismissed and the creditors/collection agencies were never paid any money as a result?
The company(ies) can continue to accept the client's payments per month, and put that
dismissed debt money in there pockets?
I know that this is very possible, because now that consumers have been able to educate themselves on FDCPA rules and Fair Credit rules. How do we know that this has not been going on since the beginning of these programs?
How can we check this out?
Even if the "negotiation" company(ies) state that they are providing settlement proposals to the client's for their approval before paying any settlement amount.
How do we know for sure that the creditor has been dismissed or truely settled?
Unfortunately, client's are not able to see the real results.
What does it REALLY mean when a these company(ies) state that they have already established relationships with the creditors and collection agencies?
Do they give them a piece of the action?

It can be put in writing all day long, but what is really is happening?
How can we find out BEFORE entering into any of these Debt-Relief Programs?