everythings normal here

I only use budget sketchbooks but somehow hadn't tried the iconic Canson XL Mixed Media sketchbook, until now! I got a partially used one so I don't know what sort of conditions it was stored in, but the paper sizing has deteriorated which lets paint to soak through to the back in a dotty pattern. This actually makes my skin crawl:

It seems like heavier opaque pigment particles like the white in the lilac don't soak through, but transparent fine-grained colors stain the spots that have gone bad. Even if the paper wasn't defective I don't think I'd like the medium-grain surface which seems fragile when wet and buckled a lot.

Comparison to other papers:

Strathmore:

I've tried their mixed media 200 series sketchbook, mixed media Vision (which had 200 series paper), mixed media 300, and watercolor 300 and 400 series papers. They all had an especially hard and smooth surface with "hard" sizing, meaning the surface didn't like absorbing water and was prone to pooling and making unwanted edges. If I actually wanted to do mixed media I would hate how slippery the surface is. I ended up "sealing" any page with graphite or colored pencil with a light wash of watercolor because even the slightest bit of friction would make things transfer to the other page. Even watercolor and ink would rub off a lot. I still think I'd enjoy the painting experience on Strathmore mixed media more than a non-defective pad of Canson XL mixed media, simply because the surface is much more durable and I'm confident that the paper would retain its sizing for longer. On the other hand Canson XL watercolor paper is much more predictable than the Strathmore 300/400 watercolor paper (apparently cotton Strathmore 500 behaves very similarly). I don't like the regular grain of Strathmore and washes dry flat and weird and unappealing... it's hard to explain. I will give Strathmore points for not deteriorating in long-term storage- my 6 year old page of 400 worked like normal while random sheets of XL are already going bad around the edges.

Royal Talens:

I'm using an Art Creation sketchbook right now. Pros against Canson: there are more pages, its smoothness is better for penwork, and it has a nice hard cover. Cons: the paper is distractingly yellow, especially compared to Canson's extra white color. The higher page count is due to low paper weight (though very close to Canson's) and water make this buckle a ton. This also has a relatively weak paper surface that can't take many layers. I prefer this paper for drawing and pens but it's too lightweight for liquid media.

I have a Fabriano 1264 Mixed Media pad that I haven't used, but the medium grain tooth feels very similar to Canson XL.