Last year at Forge Midwest, we had a 'dealers table' set up for about half an hour, mostly as an afterthought, but it was something that was discussed on and off previously.  I made a few sales, and got to chat with Matt Snyder who was sitting next to me, but overall it was 1) boring, 2) low sales, and 3) most people were playing games or getting dinner anyways.

Also, the whole point of these cons is to play games, not buy new ones.  So it makes sense that selling games isn't going to be the focus of the event.

But!  I like to try games before I buy them, and conventions are a good place to do this.  And I like selling my game, because that way I get money to buy more games.  So I at least benefit from having my game and others on sale.

So here's one suggestion for a way to sell games at an event where selling games is not the focus:  a display table, with copies of various books that people have available to sell, and a note on who to talk to.  So I might have a copy of Awesome Adventures on display, Ron might have Spione and Sorcerer, etc.  People who aren't gaming can flip through the copy that's out there on their own time, and come up and talk to the person in question when they want to pick up a copy of something.

So will these display's have author photos? Anyone new-come to one of these conventions may not know the face to put to the name, and even with nametags, you may not run across who you're looking for.

Now, I've never been to one of these, so it's quite possible this isn't a concern at this particular venue, but it is the first complication that came to mind from your suggestion.