Not trying to invalidate your experience -- I've see with my own eyes a similar thing happen with rubberized coatings on laptops & keyboard wrist rests (other's not my own).
Just putting it out there that it's by no means the universal experience.
https://www.reddit.com/r/logitech/comments/1nq2luo/got_the_m...
Everyone had the horrid goop issue as well, you're not mad.
Wish I could find a better mouse I like as much as this one that I didn't need to pay a yearly subscription for. It's just the right size, lightweight, wireless, and being able to store the customizations to on board memory is nice.
Every other mouse brand I've used (razer, hyperx, reddragon, steelseries) has outlasted my logitech-G mice, and felt noticeably better built. Their keyboards are the most generic, nothing-special keyboards for any company of that size. They don't innovate.
I will never buy a logitech mouse/keyboard ever, especially with the options we have today.
It's so tiring hearing people praise their hardware when they've literally been outcompeted for a decade at this point. Their webcams, and other niche stuff (like flight sticks) may be fine, but their mice/keyboard are below average.
I used to be the type of person that liked mice with >3 side buttons and programmable firmware and all that, with a shape that fit my hand, but lately I'm of the mindset that anything that can be done with a keyboard (or voice) should just be done on the keyboard.
I enjoy lightweight gaming-focused mice. Just anything cheap and light, and on the go, I just use my trackpad. Absolutely no reason to spend 90 bucks on a mouse unless you do most of your work on a mouse.
I barely ever hear someone complain about the hardware quality of Logitech mice and keyboards, even before considering how much of them there are compared to Keychrons, Duckys, or all the gamer brands.
The MX Ergo form factor is the best, by the way. Few people go back to pushy-pully mice after they got a taste of how fast and precise they can be with a thumb trackball. I always find it interesting where I see them on TV or YouTube: medical laboratories, architectural offices, movie studios... and Louis Rossmann's desk. I've been using them since the 90s and they probably were an unfair advantage in FPS LAN parties =D