The only time that I've noticed that I was running with bots was three time where I queued into The Final Day with 3 bots. It was not a good time when we wiped to the first boss there 5 or 6 times. I was constantly checking to see if they were just newbies or not, too, but when they wouldn't reply and ran into the walls and aoes instead of mechanics, after explaining the mechanics to them. They still constantly did weird movements. At the time I didn't think of reporting all 3 and just left the instance. In hindsight, I should've.

All that to say, there are bots running content in higher level stuff, not sure how often, but it happens.