It's easy when you can submit them and immidiately "okay" them as well.
Okay, it took me around two months, but I checked all 175 issues of Marvel Comics Presents
Roughly half of the issues were missing all or some editor credits. Around 20 issues had no creator credits at all (but stories and characters listed), around 10 had only the creditors listed the person who added the issue in question obviously liked (Jim Lee, Rob Liefeld et al.), 2 or 3 had wrong creators listed, around 20 had all creators lumped together and not attributed to the story itself and around 10 issues had wrong or missing cover artist credits.
I also merged the following duplicate creators into one single entry:
James Fry (2 entries)
S.L. Gallant (3 entries)
Andrew Hennessy (2 entries)
Chris Cross (2 entries)
Dreamer Design (2 entries)
Ariane Lenshoek (2 entries)
Scott Elmer/Pond Scum (2 entries)
Michael Higgins (4 entries)
Jack Morelli (2 entries)