I made one of those boa yarn leeches today, and good grief it was ugly. Do you have a pic of your leech....maybe it will help me make a better fly next time I attempt one of them.
They are sorta ugly...but once you get them in the water, the material smooths out, flows and moves really well.
Here's one I did. I'd just caught a fish on it, so in the picture it is still damp.