You can "try" anything you want. However, Colorado courts are not very receptive of these arguments, so if you get a particularly annoyed judge, they could order you to pay the attorney fees of the other side if your case is deemed frivolous (and that order would not be lumped in with the foreclosure fees and costs).
The rest of your statement is too fact based to address, because you think something is fraudulent doesn't make it so. Many courts take the position that the debtor (you) cannot even raise the assignment issue for lack of standing to do so. Assignment has to do with the rights of the parties (or lack thereof) to the assignment. In Colorado, since we are Deed of Trust state with power of sale foreclosure, the assignment issue goes to who gets the money from the foreclosure, not the inherent right to foreclose (because the public trustee does the foreclosure).
This is a theory with little case law behind it, but the confusion caused by mishandling the case has made life uncomfortable for some holders of deeds of trust and notes. There are counsel out there that handle cases under this theory...but I'm not one of them and I don't agree with the theory. Good luck!
This general response is not intended to be legal advice because I don't have all the facts. The particular facts in each instance will change the recommendation significantly. Any statements made in your posting on Avvo are not protected by the attorney-client privilege because they are shared with third parties. I require a written contract for legal services, so an attorney-client relationship may not be presumed merely by my response to an Avvo posting.
Due to the fact that Colorado is a lien theory state, the MERS argument is not very strong. It is difficult to prevail in Co in a quiet title suit as a method to block a foreclosure. In Colorado, there is no requirement that the Deed of Trust be assigned. The Deed of Trust automatically follows the note when the note is sold and transferred. Therefore, it is very difficult to prove that the chain of title is broken. However, sometimes the assignment can be used to show that the foreclosing lender does not own the loan or that they obtained the loan after the foreclosure was initiated.
If your sole argument is standing, you do have the ability in Colorado to contest standing within the foreclosure process under CRCP 120. If you are currently in foreclosure, I suggest speaking with an attorney as soon as possible.
This is not intended to be legal advice. Please call The Gantenbein Law Firm at 303-618-2122 if you need legal assistance.