Anyway... A few people have posted before about spine issues with Marvel Omnibi.
I finally got Secret Wars II (from cheap-comics .com) about a month ago and it had same issues.
Obviously, this is nothing to do with the seller, but a fault at the manufacturing stage. I wasn't going to send it back (they're in the Netherlands!), the shipping would be too expensive.
So.... I decided fix it myself. Did a bit of reading first about book structure.
If you open a Marvel omnibus, and look down its spine, you'll (hopefully) see a piece of thick brown paper glued to the spine.
This is is the spine lining, and is important in adding structure and solidity to the spine.
I found some useful definitions at The Book Arts Web Glossary:
LININGS are layers of cloth ( super) and paper used for reinforcing and stiffening the textblock spine. One or two layers are frequently glued to the textblock spine after it has been rounded and backed.
Super is usually the first spine lining, and the second lining is a strip of light weight paper, called a paper lining.
In some modern publishers bindings super may not be used at all (or be of inferior quality) , with only a paper lining being glued down. Ideally, textblock spine linings should reinforce the glue and help hold the sections together.
SUPER is an open-weave variety of coarse sized fabric-usually muslin or something looking like cheesecloth-used for reinforcing or stiffening the text block of a casebound book. The super forms the first spine lining on a textblock spine of a casebound book.
The excess (super hinge) that extends (usually one inch) beyond the edges of the textblock spine is used to attach the textblock to its case. It is also called mull, crash or super.
O.k, if you look carefully, you'll see that the paper lining extends to the edge of the spine, but not beyond.
So it is a paper lining, not a crash, super or mull.
It doesn't make a whole lot of difference (well actually it DOES make a difference, but that's not important here).
The point is, the lining is there to solidify the structure of the spine, but is not involved in attaching the textblock to the cover boards (as a crash/super/mull would be).
Here's what my omnibus looked like:
1. The book, without dust cover.
2. The spine, looking from above.
3. The spine, looking from below.