Spurred on by whl's observation that the bogus number retrieved for my home phone by the stock telephone voice dialer on my Nexus 5 was, in fact, a garbled phone number that a search engine was returning for Homewood Suites in San Diego and the long thread discussing the flawed dialer on the XDA developers forum, I figured that maybe it was time to report the bug. So I sent in the bug report via e-mail and was engaged by first level support.
Fine. I swapped e-mails with first level support until they finally figured out that I was complaining about the phone's voice dialer, not the "Ok, Google" functionality. And then they gave me the script for things to do on a wonky device.
I figured I'd go ahead and execute the script, which I did to no avail. Except that there was simply no way that I was going to run the "Factory Data Reset", because I didn't feel like spending hours putting the phone back together after executing the equivalent of "Let's reinstall Windows now," which is what tech support everywhere seems to tell you to do when they're run out of good ideas. Further, he seemed convinced that if reinstalling the OS didn't work, then I obviously had a defective phone which would need to be replaced.
I was equally convinced that this pretty much had to be a software problem that was not going to be improved by my wasting several hours, let alone getting a replacement phone and then wasting several hours reconfiguring the replacement.
But there had been a number to call in the message, so I did. And I got another first-level tech who asked me if what I wanted were the instructions for the "Factory Data Reset".
Well, no. What I wanted was a supervisor.
And eventually, I got one. And I explained the problem to him in detail and he is now going to forward it to the development team with my good wishes.
I already found a workaround in the XDA-developers thread above -- if you tell the "Bluetooth headset" to go to the "Ok, Google" search engine and dialer, it will allow my car's Bluetooth to bypass the broken stock telephone voice dialer and use the one that works.
So I am ok for now and we'll see what happens next.