Well "easy" is a relative term, and I can say straight away that they are easier than cats, with whom I've had almost nil success in training over the decades, and harder than my husband (who've I've trained to wash up by the simple method of "forgetting" to start preparing another meal until he has done it).
But seriously, how trainable are they? Llamas, I mean, not husbands.
I think I may be guilty on this website of showing you far more of my successes, particularly with the video clips, but too few of my failures, though I do write about them on my blog frequently, if anyone ever reads it. I have to say, indeed I have always said, that I have found my two girls untrainable as regards hands-off work such as sitting to verbal command ..and have had little success with other girls that I've worked with, albeit briefly, over the years.
So what about the boys? Yes, provided you are prepared to put in a lot of time and prepared to handle frequently, male llamas of a certain temperament respond to training so long as the training conditions are right. Anyone who has trawled through my long list of "Things I've Learnt the Hard Way" will know that there are so many ,many conditions ( eg .wind, distractions around the field, presence of other llamas, "spit" from another camelid, etc etc ) that make training these animals of prey difficult and at times frustrating.
In trying to decide if llamas are really easy to train, I also have to consider the many, many e-mails I receive through this website about the difficulties other owners have with their animals. And I get some shockers!
So...if you are intending to go out and buy your first llama, and you want something other than an animal gracing and grazing the field. ie, you want a llama you can catch, halter and lead, make sure that the breeder you are approaching can do this and can demonstrate that he/she can do this. Dont expect to be able to do it yourself; llamas can be shy of unfamiliar people and this is something to work at afterwards, but do make sure it can be done by someone: I get so many e-mails about uncatchable and unhalterable animals. Infact I've got an uncatchable girl myself. She has changed hands many times and I dont know her beginnings, but I wonder if she was ever catchable!
And yes, there are a few animals that respond well to operant conditioning training as you may have seen on this site. As Jim Logan says, it should be possible to train some llamas to do anything, off-lead, that it is physically capable of doing...so we are effectively putting some of them in the same class as dogs and dolphins. But I stress that, in my experience, it is not every llama that is receptive.