gnus-article-boring-faces

gnus-article-boring-faces is a variable defined in `gnus-cite.el'.
Its value is

(gnus-signature gnus-cite-1 gnus-cite-2 gnus-cite-3 gnus-cite-4 gnus-cite-5 gnus-cite-6 gnus-cite-7 gnus-cite-8 gnus-cite-9 gnus-cite-10 gnus-cite-11)

Documentation:
List of faces that are not worth reading.
If an article has more pages below the one you are looking at, but
nothing on those pages is a word of at least three letters that is not
in a boring face, then the pages will be skipped.

You can customize this variable.