Poorly drawn and childishly drawn porn (a la Deviant Art) terrifies me. One half is the subject matter (whoever made the sonic toilets needs therapy) and the other half is the almost pseudo-innocence behind it. It's the realization that not only does the author do not see such horrible things like vore, unbirth and transformation as terrifying or disgusting in the slightest.
Also female dominiation can get pretty cringey.