Ok, so I've read the all the rules for bumping (I think), but it seems to me like these are ignored, and that they are not followed up. What are the rules for bumping,and are there different rules for bumping in marketing boards?

Marketing board now allows you to just "bump" a thread by posting "bump", it used to be illegal and only way to bump was to post a update on the item/art.

As for the other sections, a illegal bump is posting something like this:
bump
hi

Something that's useless.

Note, you have to wait a minimum of 24 hours before bumping a thread in the Market. Also once you have done this you cannot post again with updated information to act as an additional bump, this has to be included in the original bump.

Thank you for the quick answers. I found out where the market rules were too, so this thread was kinda silly.