If you hang in heart of the mists during downtimes you'll see plenty of these bots. They usually wear base character creation gear, they are paired because they duo queue and they have the same looping behaviour of taking a waypoint and then running to an isolated place of the lobby where they stack by at least 2. They wait here for their next match. Those are the most obvious to spot, they usually play core guard or core necro.
Then there are the scourges and mirages bots, which I don't think operate the same AI as the previous ones and use geared characters. You can spot them in combat through their behaviour, but you may also encounter a regular bad player.
As far as my observations go there are at least two kind of bots with their respective behaviours patterns, the best way to detect one is to add them to your friend list and see if they have an absurd amount of matches played.
One last thing, it's pretty easy to find how to operate such bots just by googling it. It's up to Anet to take measures to adress this, and players who deny their existence are either playing in high divisions or are blindfolded.