Is fine if they depict games they EXPECT to be played.
If it were just pictures of the games, I might agree, but these were full-fledged games in progress with many people sitting around them. And does it matter if those games are actually present?
There were pics with vendor/publisher booths in the background as well as employees of a company or two. They weren't there and weren't going to be. I wouldn't have looked at those pics thinking a specific vendor/publisher was going to be there, but I would have thought there'd be a stronger vendor/publisher presence than there was.
I found a place where con-goers have given feedback posts and those few who've posted seemed to enjoy themselves so I guess I should just shrug and let it go. As has been said, ultimately this type of advertising will either drag the con down or build the con up based on what the people think.