Anything gross like fart fetishes, scat, diapers, etc.

This.
Gore fetishes, too. None of that please.

Same for me, anything gross, too gore. Stuff that involve big age difference/incest too (especially the "daddy" thing, ew)

I want to strongly preface this that my objection to any sort of content is never intended to tell people what they can and can't draw or what viewers and commissioners should and shouldn't enjoy. To each their own.

The only reason content would scare me away or make me unwatch somebody is if they started making exclusively or almost entirely that content. If it's just the occasional piece I can just as easily pass it by and wait for the next piece of artwork containing stuff I do enjoy. The stuff I don't like to see:

·gore/blood
·violence/war/fighting/battles/guns/swords/death
·suicide (I almost unwatched a very good artist once because I inadvertently clicked on a piece showing the most disturbing suicide scene I've ever seen and couldn't tell what it was from the thumbnail; it should have had a custom thumbnail displaying a warning)
·vore/vomit
·body and facial piercings (a turn-off for me)
·excessive tattooing
·characters that are hugely muscular and bulging, especially if taken to a grotesque extreme
·scat/shit/fart play
·diapers
·religion and religious symbology of any kind
·drugs/pot
·smoking
·excessive drinking
·micro/macro
·hyper-sized anatomy
·inflation/living inflatables
·morbid obesity
·characters referring to a lover as "daddy" (or "mommy" for that matter)
·mpreg (male impregnation)
·rape or apparently forced sexual activity of any kind
·BDSM (a collar and leash is fine)
·master/slave dynamics (whether relationship dom/sub types, sexual slavery, or actual chattel slavery)
·humans/humanoids/neko/characters with facial features that look too human
·zombies/living dead/skull-faced characters
·and probably a couple other things I'm forgetting

There are certain character types that I don't care for such as snakes, reptiles, and aquatic creatures, but that's just a matter of preference and I don't consider those objectionable or outright offensive like the things I listed.

Nothing.... hehe