Scat and gore are allowed as long as they: are always spoilered (if not spoilered, they will be spoilered by a mod without punishment) and kept to a single thread each.
Do a reverse image search before you beg for the source of an image. If your efforts are fruitless, ask for the source, but only if previous requests have not been made (don't spam "SAUCE?").
Keep threads relatively on-topic, at least as far as images go. Discussion can wander, but the image topic has to remain consistent.
All images should be tasteful and relatively high quality. In other words, don't post pictures that most people would consider to be garbage.
Post at least 10 images in a new thread, and be sure to check the catalog before starting a new thread. Threads that violate this rule may be deleted without notice.(NOTE: Some threads don't need 10 images, like stories/writefag threads).
Post source requests in the stickied source threads. It keeps things tidy, and makes your request more likely to be seen. Threads like "Hey, /d/, post X" without posting at least 10 images yourself should instead be posted to the sticky.
Shitposting is tolerated, but don't de-rail a thread simply because you don't like it. Excessive saging is a 24-hour ban (Don't just say "sage" 10 times in the thread. This applies to dubsposting, too)
If you have any questions or opinions about the rules, post in the sticky.