I'm looking for a word for "bad prose", as it seems such a vital concept. not much to report as yet, but I did find this Brit. usage, which has the right sound:

tump..
4. fig. Trivial writing, bad prose.

1917 KIPLING Diversity of Creatures 172 It's the most vital, arresting and dynamic bit of tump I've done up to date. 1933 D. L. MURRAY Eng. Family Robinson ii. 36 Did you ever read such tump as our parish magazine?

edit: I guess hack-writing would kinda qualify.