I guess my question is to some extent academic, as I don't often fish for trout and when I do I like to use the "trout flies" that I like to tie but usually only use on bluegills.

But it is interesting--when I think about it, I don't normally use cork poppers for bass. I usually use Gurglers, spiders (which are shaped like big ants, imho) or what could pass for large terrestrials, like a madam X or a UFO. So maybe the line between the two is a little blurry, and depend on matching the fly to the circumstances (as always). Trout and bass both take buggers, right?

Thanks for the answers--