I have purchased a number of nursery plants this year and have found that as
I get into the process of combing out the roots - they are an absolute mess.

My sympathies. I have had the same problem not only with nursery trees and
collected trees, but even trees from reputable bonsai nurseries. Straightening
out the roots when they repot is labor intensive & not cost effective. See
Julian Adams' article in a recent issue of International Bonsai.
The only thing you can do is start by overpotting in a large training pot that
will accommodate the roots. Some of them will stick up. Prune the mess off a
little at a time. Repot yearly & gradually work the roots down. With conifers
it will take longer than fast growing broad leafed trees like maples. The worst
problem is when you have a few large roots with big gaps in between. If you
can't convince the tree to grow new roots, you will have to get grafts from
somewhere.

Saturday I spent over 2 hours trying to comb the roots out on a Mugo pine.


You may have killed it. You can't do that to a pine tree. You have to
straighten the roots out very gradually, always leaving some of the original
soil.

I believe someone else mentioned a similar problem with a Hillier Elm not
too long ago.

I had a 'Jacqueline Hillier' elm from Iseli Nursery where the root ball was as
solid as a rock. I finally had to saw it apart. By some miracle, the tree is
still alive in its bonsai pot, but there is a mass of surface roots which will
have to stay until the next repotting.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)