How can I predict whether an LCD clock will "fade" over time? [closed]

Like many people, I take a small travel alarm clock with me when I travel. As a matter of personal preference, I don't like to use my phone for this and I don't like analog clocks with hands. I want a digital display and a physical snooze button. This sort of thing:

Every few years, I buy such a clock, and for a year or two I really like it and am glad I replaced the old one. But then the numbers become hard to read. They aren't as dark, I think. Sometimes I can read them if I hold the clock at just the right angle. Generally the button you push to light up the background just makes it worse. Eventually I end up having to replace the clock, and the cycle repeats.

What is the property of the clocks I choose that causes this? Would I be better choosing an entirely different technology other than these black-segments-on-a-grey-background clocks? Replacing my clock means learning different gestures to turn it off or snooze it, or to confirm that it's set before going to sleep, and this has led to mis-set alarms, failure to wake, and taking too long to turn it off when the alarm starts beeping in my bag. To prevent this I would like to buy one clock that I can use for a decade or more instead of a new clock every few years.