I dunno about you guys, but when Sage and I are in the mood to watch porn, we generally aren't looking for stuff with plot, just stuff with sex. That being said, we wouldn't pop in an all-sex porn before we've even taken our clothes off. I guess for us, porn is more useful in the background, so that you can hear it and occasionally see bits of it, but not so much for sitting on the couch and watching.
Personally part of the appeal of having porn on while we have sex is that its like being around other people having sex without actually having to be around other people having sex... just the room filling up with sex noises from us and the porn and being able to see us having sex along with other people having sex makes it feel like being in the middle of a big juicy romp with lots of people in the middle of a Roman bath house or something. But then I guess that sort of thing turns me on.
In short... how many porns have you seen that have a plot you wouldn't just laugh at or dismiss as dumb? If having a dumb plot is the problem then I'd say you need to get some porn that doesn't bother with plot at all.
As far as where to get good porn goes, feel free to PM me if you need a good torrent site or two.