I don't know anything about this, specifically. But for consideration:

You know those ads that puzzle you and leave you examining them, trying to understand what they're saying? They've just grabbed a chunk of your attention.

(And a lot of ads, these days, are designed to leave a memory of the product, preferably associated with an emotion, lodged in your sub-conscious. Not to sell you outright, but to be there, lending familiarity, when you are at the point of selection and purchase.)

Anyway, I wonder whether the difficult to read spines are more noticeable and so grab desired attention in certain contexts.

Or, they just have a crappy graphic designer. ;-)

I just skip over the unreadable spines and the CDs produced by mystery bands, especially when confronted with a large selection.

It doesn't really matter when physical media is no longer required or desired. Books, DVDs. CDs and such like are going the way of LP records - quaint, for gifts and decorative purposes. In this brave new world it is how good the gift-item looks on the covfefe table that matters. Even then the book will be migrated out to storage and the charity shop in due course as nobody has space for clutter these days.

What I am disappointed with is how we used to have mostly Penguin Books and their imprints, all with uniform and good looking spines. A wall full of Penguin Books looked awesome. But then we moved to this 'pile em high' retail model where the designers took over the cover designs to jazz them up and make them the bestsellers we know today.