How can I avoid UNWANTED UNITY updates?

[WinRiddance]

Bear with me, some explanation & background required ... Thanks!

Starting with Ubuntu 9.04 I really fell for Linux and made it my full time permanent OS after nearly 20 years with *******. Like many others here I've tried numerous distributions extensively ... Debian, Suse, Fedora, Mint, and so on. Xubuntu along with Compiz and more recently Mate is what I like and prefer, been using those for the past year and a half. Since I don't like or want an Iphone and since my cell phone is nothing but a phone, I have absolutely no use for the Unity desktop. I'm extremely pleased with Xubuntu because it provides me with the ability to customize anything & everything relatively easily. BUT ...

... it seems like ever since Unity came out, every few months I'm experiencing system quirks and problems that I can't help but think are related to updates that contain files that I don't use nor want. Overnight mounting issues or printer issues or other inexplicable USB issues even though the system ran flawlessly for months ... usually behaving oddly like this after an update with Unity related items in the Update Manager. I'm not enough of a Linux "guru" though to know what I should or can safely avoid. That's where I need some help. For example:

I will never use Unity nor Gnome3, period. I love Xubuntu and the freedom that it provides to me, yet every so often my software update manager contains updates specifically labeled "unity this" or "unity that" for lack of better words. Considering the fact that Xubuntu is XFCE based without anything Unity related (or so methinks), I'm trying to figure out a way to update my system strictly with the applications that I use which are relevant to my XFCE/Xubuntu environment. I find it very frustrating that Xubuntu Operating System installations don't draw their updates from an independent Xubuntu package manager ... So here's the prize question, if someone would please help me out here ...

Is it possible to have a clean installation of Xubuntu ... followed by setting up the update manager in a way so that only XFCE related updates are received, while Unity updates are being ignored ... and if so, how would I go about achieving this?
I don't ever want anything Unity or Gnome3 related on my system unless it's Linux/System imperative for my Linux (Xubuntu) OS to run stable in its current configuration. I would also love to know how I can avoid third party "Unity" updates for applications like LibreOffice, VLC, and so on?
Thank you so much in advance for your time.