I think I understand how to get reasonable reflections in general. Use a reflection ray-trace node, set the background to black, plug it into the reflection input in Poser surface. Usually keep the reflection color white, but can play around with textures for special purposes. (For example, if you have a tinted mirror.) The sum of the reflection strength and the diffuse strength should be one or less.

I have a couple of questions:

1. How can I make the reflection less "clear" or mirror-like? Not necessarily weaker, but more wavy and distorted, as if the mirrored surface had imperfections or was not smoothly curved. I can get some of that with the quality input in the reflection node, but is there another way.

2. It appears that if you plug any other sort of node into the reflection input, you end up with a self-illuminating material. (This is particularly noticable when you use gamma correction.) Is there any way to get around this other than using a reflection node? I kind of like the look (in an artistic, as opposed to photoreal, render) you get with the old technique of using a reflection map as input to a sphere map plugged into the reflection input, but it just doesn't look right when using gamma correction (or even reasonably low lights), and it isn't "shiny" enough if you dial down the reflection strength.