Revisiting this, I agree that there's quite some "meh" about this. I mean, there's no way to really know how machines have and share identifiers. So one must assume that they have, and do. And deal with it.

VMs seem generally good enough. But then there's WebGL, which generates identifiers based on the host graphics system and guest virtual video driver. So all Debian VMs on a given host have the same identifier.

If it really matters, though, you gotta use different hardware.

Because the machine-id by default never changes after OS installation.

Neither does a file Chrome generates. Not even if reinstalled.

Huh?

Even if you do

    $ sudo apt-get -y purge chrome

[or whatever its package name is]?

And if necessary, find and delete everything that it created.

apt doesn't know about any file the application might have ever created in your home directory.

> And if necessary, find and delete everything that it created.

Actually, apt does a pretty good job at finding stuff. Sometimes it can't delete, but it warns you about that.

Apt only knows about the files that are listed in the package.

Sure, but then that means that honest packages should document all files that the software can be configured to created automatically. Or at least, all but user-specified ones.

In Linux, I can find and nuke everything that Chrome (or any other app) generates.