I reckon if you can perform OK at a gangbang or a party like LMP then you're at least halfway able to do porn in front of a camera, and Viagra's probably levelled the field a bit. Can't imagine it would be worth the candle though, especially if you had to travel to do it for little or no pay. Sir Frank makes some good points, and since you have no control over where porn footage ends up there would always - literally always, thanks to the web - be a risk you'd be recognised by someone you know personally.
That said, I don't think anyone else gives a monkeys about the face behind the cock on camera, or would recognise a male porn performer on the street. Probably more of a risk for a female performer.