Yeah, I use them commonly.
- Freshly stocked rainbows love them. Typically my first choice just after a stocking, and still 2nd or 3rd choice even after they've been in the stream a month or so and have picked up on some natural food items.
- Rainbows in general seem to like em. For wild bows they usually aren't my first choice. But when nothing's working I still tie one on and they usually avoid the skunking.
- Browns, eh, seems that for them to work, REAL eggs have to be on the natural dinner plate. That does happen, for instance during sucker spawning runs in early spring, or lake-run browns chasing steelhead upstream. They can be deadly on browns in those situations. But the rest of the year they seem to get ignored an awful lot.
- Brookies are somewhere in between. They seem to hit just about anything decently, but there's no "magic trigger" like eggs with bows or baitfish with browns.
As far as color, if there's a natural color, match it. Otherwise, dark, opague colors for cloudy water conditions. Deep red, bright pink, chartreuse, etc. Lighter, pastel type colors for clearer water. Cream, light pink (salmon), peach, etc.