Good to see local media starting to cover HCAD's corrupt tactics. I hope you don't mind, but I reposted your article on the blog, "The HCAD Wall of Shame" (http://hcadwallofshame.wordpress.com/) that documents corrupt behavior by HCAD that I and other contributors have experienced, and I welcome anyone here to contribute their experiences to that blog.
HCAD routinely lies to property owners in informal meetings, and appraisers will often let it slip that they have no intention of lowering an appraisal before they have even heard your evidence (see: http://hcadwallofshame.wordpress.com/2012/07/09/alex-t-ton/). The ARB can be just as bad. Some ARB members are truly there too help taxpayers, but many are just there for a power trip, will violate procedure and are often racist (see http://hcadwallofshame.wordpress.com/2012/07/18/verdeen-newton-doris-butler-and-pauline-newman-2/).
And good luck filing a complaint. I filed a very detailed complaint over impropriety of an ARB board member, and got a short letter back saying they had found no impropriety, with no elaboration. When I demanded to see copies of all information related to their alleged "investigation", I got a letter from the County Attorney stating that all that information falls under attorney-client privilege, and they even petitioned the State Attorney General to declare it privileged, which he did. I have left messages with the State Attorney General's office which have been ignored.
Again, I encourage everyone to submit your HCAD horror stories to "The HCAD Wall of Shame" (http://hcadwallofshame.wordpress.com/).