A very interesting thread.
Thanks for all those tips, Colin. They are very helpful, as always.
I don't have patience as much as you do, nor the kind of sense of humour you do.
I don't do formal portrait, but when I am doing some informal portrait and I get these weird expressions, all I do is, show the picture to the model and ask them if that is what they want. After 2-3 reviews things start to improve