I've personally witnessed someone using a bot for Alexandrite farming. They were in Middle La Noscea and as soon as a FATE would spawn, they'd mount up and take the longest possible path every time. (most people would jump down to the western half of the map, this person took the ramp down EVERY time) There were also other little things you could tell they were using a bot, such as if they were in combat and another FATE spawned, they would just stand there until the mob was killed. (either their chocobo or another PC would have to kill it for them to move onto the FATE, but they wouldn't personally do anything to try to kill the mob or get out of combat)

I'm not going to go as far as to say it's ruining my gaming experience, but it is pretty saddening. I've ran into other people that use bots to spiritbond by standing in out of the way places and obviously botting, since their character just sits in one spot spinning in circles until a mob spawns. I just report them and move on, but that same person is still in game so it's a bit disheartening.