I don't get it, why are the doodles horribly embarrassing?

I'm not the person who wrote the description, so bear in mind I could be totally wrong about this.

But a lot of artists - well, definitely me at any rate - have this hangup where we're really embarrassed to show off sketches, doodles, or art that's unfinished/still in progress, because it's not our best stuff. Or it could also be old work - stuff that's horribly bad because we weren't as skilled or had different interests back then (never mind that literally everyone grows and changes, showing me my old work is a lot like showing a cross to a vampire XD )

Sometimes I'll do really crappy sketches just for the sole purpose of warming up, or as a way to solve art block or work out the specific pose I want. (Art isn't magic, it's work! Just like everything else! lol) Those are very important to do for their own reasons, but those sketches aren't necessarily ones I'd show publicly.

Some artists also use their sketchbook as a diary, and can write down or draw things related to their personal feelings. So it'd be kind of like an invasion of privacy in that case.

But again, this is just speculation on my part. The description could have nothing to do with any of that.

I like Rakumel's interpretation (I also have lots of bad sketchy drawings I'd rather not have people look at, hah), but another idea: could be a "Whoops, my teacher caught me drawing unicorns instead of taking notes..." The notebook paper and quadratic formula make it feel school-ish to me.

(Rewording my answer to try to make more sense)

I don't feel like anything actually represented on the item is embarrassing but I suppose the description is alluding to all the cringey stuff some of us liked to scribble and sketch in the margins of our school notebook, such as that "haha I'm so rAnDoM" stuff (I was a big offender in that regard) and maybe names of crushes or something. That's my interpretation anyway.

Its more the nostalgia tied to doing those doodles. The S mark, the little faces and stars and rainbows are something nearly everyone ever doodles rather than doing class work. Yet we never wanted anyone to look at them