One of the problems compounding unusable UI that I've noticed is the trend to use as little text as possible.
I can understand why designers and even developers want to not use text: Handling multiple languages is annoying and getting people to read is impossible.
But you know what? I don't understand what that fucking black-and-white hieroglyph you pulled out of your ass five days ago fucking means.
For booleans I tend to prefer using “Enable/Disable”. In this example, “Disable Flash” with a checkbox that is clearly in an “Enabled” state can reduce ambiguity. Alternatively, displaying the state and using tooltips that describe the action can be great, but falls apart on mobile devices.
That leads to the extremely common confusion of if "disable flash" is a description of what you will do when you interact with the control (the verb describes the action to be done), or a description of the current state (it's a "yes, disable flash" confirmation). Both are common. Some apps even use both on different controls.
Compare that to a checkbox next to "Flash is disabled". Or a toggle. Or a button. The control and its vague state or bad color blindness choices doesn't even matter if you're clear with your words.
"Flash mode" is the problem.
"Flash is on/off" is the solution.
("is" is important here. "flash on" has many ways to be interpreted because it's missing a verb.)
Your UI should be understandable from text alone if needed.