I've not flown a trainer yet that will self right despite the adverts, maybe if your a little off perfect it will come good, IF you've got it trimmed right at right power, but your not in trouble in those cases. but i've seen trainers go in because the student got it all wrong and let go to wait for the trainer to recover, what you can say is they all want to roll in and hit just past vertical.
a Lazy bee gets closest to self recovery