I've come across a trick for dealing with the teleport-shoes-up-ass issue. No guarantees, and it won't work in some sims, but it has worked for me every time thus far.
Fly before you teleport. Just get your avatar off the ground. Teleport, and wait for the new sim to rez a bit before you touch down. Something in the sim rez process seems to be causing the problem for me. Letting it unfold before landing helps.
This won't work if a sim is a no-fly-zone, but give it a try otherwise. So far, so good.