Interestingly, the effect was discovered by the neuroscientist purkinje while at the beach as a boy. He noticed that waving his open fingers over his eyes produced geometric hallucinations and later published his drawings -- back in the mid 1800s.
"The first phenomenon described by Purkinje was novel: He produced flicker, while looking at the bright sky, by waving his fingers in front of one eye and reported seeing checkerboards, zigzags, spirals, and ray patterns (see Fig. 3.2, Figs. 1–4). They were called shadow figures by Helmholtz (1867, 2000b) and are now referred to as stroboscopic patterns (Smythies, 1957), although they were described before the stroboscope was invented."
Just below ... "Anti-Gravity" :-)
Of course, it’s still a dumb product since you can just check whether written text changes when you’re not looking at it, but it’s not necessarily as dumb as it sounds.
I haven't tried, but I can imagine blinking lights always present would be a much bigger clue to me.
I'm not really sure what I'd do differently in a lucid dream anyways, my subconscious seems to have a better imagination than I do. Remembering more details from dreams would be more important for me I guess.
To throw an anecdote into the bucket, I've had a dream where I read a word, and it didn't seem to change on closer inspection, and I remembered it when I woke up. But it didn't cue any lucid dreaming.
But I'm also out of the habit of checking.
Endorsed by founder of bulletproof coffee, which says something.