-> pornographic images, videos or games

This could be the problem. We have pictures form the porn movies, we mentioned this in the comments, sometimes we use words "sex", "bottoms", "porn", "breasts", "rape", etc...

-> transparent clothes

How much transparent?

-> obscene or provocative posture

Even in the clothes, I presume...

Breasts are bad, but blood, death, body parts, drugs - not... It's just stupid.

Maybe You should move all porn movies and sex related (with naked people in the main pictures and in the comments) to the section available only for the registered members, with confimred age? This would be simpler (and more sensible) than cleaning site and censoring pictures...?