“Isn't it erotic? Don'tcha think?”
What any person finds erotic as opposed to pornographic tells the amatuer psychologist a lot about that person. Consider the elderly spinster aunt, who reads tales of bodice-ripping passion written in small books by homosexual men using women's names. She would find the tales of lust to be "erotic". Yet, if she were to be confronted with a video or DVD depicting the scenes portrayed by actors, she would consider the same tale "pornographic".
Consider another case, the middle-aged single man. He may consider viewing the nubile woman next door, covertly through a hole in the wall as she showers, to be "erotic". Yet, if he were to see the same woman naked oil wrestling with her lesbian best friend, he would consider that "pornographic". And therefore, ten times better. He would sleep well that night, ladies and gentlemen. Oh yes.
While the human reproductive act naturally requires a generation and exchange of bodily fluids, material deemed erotic often completely ignores this component. Pornography, on the other hand, so to speak, revels in fluids. While being much more accurate in its portrayal of the human act of love, the mention or concentration on fluids gives pornography its "dirty" connotation.
Additionally, material is more likely to be labeled as pornographic if it is a visual depiction of the sex act, rather than a description. Certainly, one is free to go into nearly any public library and find graphic descriptions of every kind of hump and squirt, from the tender first caresses of awkward teens to anal adventures featuring kitchen appliances, readily available to any curious youngster who has learned to read. One curious aspect of this is that simply because men generally respond more to visual stimuli than women, and thus men are more often labelled as pervs and slimy horndogs. But this sort of gender discrimintion is as common as a cold, so don't even bother fighting it in court.