I get the older ones from the NSPCA and it takes a little time to get them use to the new everything and the rules. But that said I have 9 right now and they are all great. Each with a different personality. My herd ranges from 11 years to 16 years old and some came already trained to use a doggie door. Some were not sure what I wanted them to do but after a couple of days. They got the just of it.
They are smart little ones. Take the time to make sure that they know what the rules are and they go well and so do I.