With the pine bark beetle infestation here I've become at odds with myself on the same questions. At this point in time so many of the dead trees are too far gone for safe entry and dismantling. So I've turned many down. But certain ones I do go ahead and climb always leave a certain feeling in my gut, maybe this is going to be the one.
For the most, in our coniferous stands, there are ample sound trees for tie-in-points to work out of, and even double tie-in-points for dropping down on the tree in question. In those situations I feel pretty confident, but the lone wolf out by itself is another tree all together, no way out there. And that is a different matter.
There's tens of thousands of dead pines here and years of wondering ahead.
Jerry B