Things that really turn me off are:
beards, although I often like thin mustaches
condoms - although people should wear them, they should not be seen. I don't mind the condoms that you can't see unless you look closely.
prolapse of any kind
scat of any kind, although I don't mind pissing
farting
spitting into mouth, although cum is nice
hair on ass, especially in the crack
yellowish cum, although white or clear cum looks nice
blood of any kind
warts and moles
amateurish blurred tattoos - although crisp colorful ones are nice
cum coming out of ass.. but going in mouth is nice
smoking / vaping of any kind
bald heads
lack of face being shown
flab
anybody being injured or in pain, although a playful light spanking is nice
any type of humiliation
excessive bondage, such as with clothes pins or genital piercings
red hair - too distracting - although reddish brown hair looks nice
afros - although I like long hair
orgies - because the video can't capture the energy of more than 2 or 3 people at once. The camera is almost never where I would like it to be in an orgy
limp dicks - semi-hard is fine though
annoying, inappropriate soundtracks
bad camerawork (this plagues almost all OnlyFans posts)

I wonder how typical my dislikes are.