See attached. Coils have been replace once already, these are current pictures. All plumbing fixtures replaced including water heater and copper piping to water heater. What do you think?
l would be concerned big time .Looks to me like some sort of fumes is causing serious decay to the copper in this home .
tainted drywall?
One time natural gas leak? 
Sulfur water?
Marcel is right. 03 is one of the primary suspect yrs for Chinese drywall.
No well water. It is municipal water service
Hey Preston, hope all is well.
- Year Built 2001-2008----------------------Yes
- Tarnished/blackened metals----------------Yes
- Drywall thickness 1/2 " ?---------------needs to be determined
- Identify manufacture ?---------------needs to be determined
- Drywall color (white) or grey with grey specs–needs to be determined
- Odor (not all contaminated drywall smells) —needs to be determined
From what I see and my experience and with the A-coil replaced already I would be very suspicious.
Ditto from above. The blackened ground wire and copper lines and air handler replaced is not good. Client should use all available tools at their disposal, drywall dogs, IAQ, moving attic insulation, core sampling, to rule out tainted drywall.
Agree with above comments. It may be worth sending some physical samples to a lab for certainty.
How much is the house worth?
P, were those Cu entrance cables?
Tainted 
Yes on cables
I remember in one of the classes that, you can pull the baseboard out and look for the red drywall tape. An extra clue if you can’t find markings in the garage attic space.
Is all of that in the garage only? If so, chemicals stored in a garage will cause all of the above.
of course I am assuming this has been ruled out.
Looks like tainted drywall to me. At least from here!
Bert
Is the attic space accessible? If so, check the ceiling sheetrock for mfg info. If you can only find a barcode, hit me up and I’ll help you ID it’s country of origin. Do realize though, that ceiling board is always different than wallboard (in a properly built & permitted structure) therefore identifying the board used on the ceiling does nothing to determine the wallboard used. Either way, if you witness “made in china” on the ceiling board, you’ve already made your case. Further investigative measures should be recommended to positively ID the materials, and see how extensive the problem is throughout the entire structure. IMHO of course 
Would this be caused by defective drywall ? Is it not a little early for that to occur?
I was with the understanding that Chinese Defective drywall was not until 2006 to 2009. I am just taking a guess at this.
Russell
SUMMARY OF IDENTIFICATION GUIDANCE FOR HOMES WITH CORROSION FROM PROBLEM DRYWALL AS OF MARCH 18, 2011
In its continuing effort to provide accurate and helpful information, the Federal Interagency Task Force1 believes that it is appropriate to update Revision 1 to the Interim Guidance–Identification of Homes with Corrosion from Problem Drywall, August 27, 2010,2 to reflect additional information uncovered by the Task Force concerning the installation dates of problem drywall imported from China. Specifically, the CPSC has found a number of homes where problem drywall previously imported from China was not installed in homes until calendar year 2009. Previously, the CPSC believed that all such problem drywall installations were completed by the end of calendar year 2008. In this updated Identification Guidance for Homes with Corrosion from Problem Drywall as of March 18, 2011, the years of installation are adjusted accordingly, to include calendar year 2009.
There are no other substantive changes in this updated Identification Guidance for Homes with Corrosion from Problem Drywall as of March 18, 2011.
I have seen in a home as early as 2001