I'm shamefully new and inexperienced at this, but here's something very general I've noticed about the brushes I have: the ones that hold together tighter in more of a rod don't lather up as well as the ones that spread out. One particularly irritating example is a travel brush that is stored in a tight tube. I haven't used it much, and I think I'm going to have to use it until it starts to spread out, and not keep it packed in the tube--as it is now, it doesn't work at all. On the other hand, I have a $3 horse brush, wide and loose with lots of internal space, that's a maniac foam machine.

So maybe some break-in is in order?