The title says it all. As far as I understand I can pay a woman to have sex with me on tape for a porn scene, but I can’t pay the woman for sex if it’s strictly for my pleasure. Is that correct? I know there’s paperwork involved in shooting the porn scene, but I don’t understand why one is okay and the other isn’t. Can anyone enlighten me?
Just answered by Cecil.
Wow, unbelievable timing. Thanks!
I’m assuming that dgrdfd read the column, and that is what prompted his/her query.
If by “okay,” you mean “morally okay,” your guess is as good as mine.
I would assume that the reason why the “sexual performance” which is illegal is specifically that which is intended to cause pleasure to one or more of the participants is to avoid accidentally criminalizing activities which might be superficially similar, but which serve legitimate non-sexual purposes; for example, hiring a doctor to stick his finger up your butt is legal, but hiring a prostitute to do the same (unless s/he’s helping you fish out something you lost up there) is illegal. That it why it is the *intent *of certain acts make them criminal. (Actually, intent is a requirement of many crimes. It’s what makes the difference between murder, manslaughter, criminally negligent homicide and self defense.) The reason why the laws haven’t been re-written to specifically outlaw sex which is done for the purpose of entertaining others by filming/taping/photographing the activities is pretty much all about the First Amendment.
Actually I thought of this all on my own and was surprised to see that Cecil had just answered it. And isn’t dgrdfd an obviously masculine name? 
Thank you for the rest of your post as well.
This is perhaps the single most asked question on the site. Here are some links to earlier threads. I’m sure there would be more if I used different search terms.
Why is porn legal, but prostitution is not?
What’s the line between pornography and prostitution?
Are actors prostitutes when they have sex?
Why aren’t porn stars considered prostitutes?
Why is porn production legal but prostitution illegal?
Why can’t I start a porn movie company as a front for prostitution?
Cecil’s timing is always perfect. 
The question should be:
Can or would someone pay me to shoot a porn scene? Please.
Is the most FAQ at the Dope?
Anyway, the answer is WAY simpler than Cecil suggests: If you film it, it’s art–whether good or bad–which makes it constitutionally protected speech.
Which is why you should always bring a camera along if you hold up a liquor store. That way it’s not robbery, it’s performance art.
But it’s not quite THAT simple. If you film it just to avoid getting arrested for solicitation, it’s not constitutionally protected. Other examples of non-protected speech:
“Would you like to help me murder my spouse?”
“How much for an ounce of heroin?”
“Hi, I’m Lenny Bruce, and %&()# you.”
As with almost all areas of laws, there is an element of reasonableness – if it’s obvious you are bullshitting the court, you will likely lose.
It is simple: Prostitution shouldn’t be illegal.