As far as I understand it, I could be wrong. I'm not a professional. Last I checked I didn't take photos or have a pussy of my own.

Basically, if you avoid things that could be considered pornographic, vulgar or explicit, you should be ok.  It can be considered a spread shot even if you aren't assisting the spread.  And sometimes you'll see models share photos that are notallowed and think it's ok, but those photos will soon be reported and removed by admin.