No doubt a computer could filter out a list of certain words. I can't imagine how any site with public postings can be made "family friendly", without a human monitoring each photo or post. No doubt whatever standard you uphold, you will offend someone. I would wager if you check back in a couple decades a computer could filter some photos.

Also, the most offensive words often have no foul language. One can easily imagine very sexually explicit language using non sexual normal objects. Likewise to take an example from Mark Twain, I believe many people would find this poem extremely offensive. Others would consider it educational for youngsters. Yet, how could a computer determine it was offensive when humans can't agree??? Perhaps only by filtering a reference to God (since any content mentioning God will offend some sect?)

http://www.lone-star.net/mall/literature/warpray.htm