This could make a neat companion to the 'wishlists' thread - when there's so much uncollected stuff out there, where has Marvel/DC/whoever made a misstep in what they've collected? Be it down to the design of the book, the title of the book, cover art, or issues ommited from the collection, or even the reason it exists at all, or whatever - where have they screwed up?
Here's some of my thoughts -
Titles
Avengers: The Falcon, an awesome trade paperback release - but why not call it Captain America: The Falcon? I mean you have a Cap movie out at the same time, and Cap himself appears in at least four of the issues. Huh?
Avengers: The Contest - at first glance, I didn't even realise this was Contest of Champions.
Invaders: Eve of Destruction - the complete run of Marvel Universe where only 3 of the issues are Invaders. Nobody cares about proto-Agents of Atlas - some supplemental rarer Invaders content to fill up the back would have made this so much better. Of course, DC haven't shyed away from three issue trades - Batman: Faces, for example. I would have happily seen an $8-10 cover price just to have those three issues in there.
House of M: World of M Featuring Wolverine - Wolverine plays poster boy again when he makes up only three of the issues. An X-Men volume and a World of M volume collecting other stuff would have made a lot more sense.
Contents
Catwoman: Under Pressure - three of the issues are from War Games and make no sense on there own. This is one instance where I argue for 'story' over 'completeness.' Same problem with the recent Avengers/New Avengers Infinity volumes - we get half the story when it's already all there in the Infinity hardcover.
Deadpool/Thunderbolts - we get nine issues split into a 5 issue and 4 issue trade (and it's still not a great crossover either.) The X-Force/Cable volume is even more guilty of this crime. I think the more recent Cable and X-Force/Uncanny X-Force made a wise decision in making the relevant material available in both trades, whatever series you're reading.