To be honest, I only REALLY find her annoying, or anyone else's voiceovers, when it's the very start of the round, and her voice speaks over the sounds of the Zeds spawning in near me.
To me, it's CRITICAL that I know that a fleshpounder is spawning in near me, or better yet, a group of gorefasts or any other group actually spawned in RIGHT NEXT to me.
That's one spawn that I absolutely hate. Turn your back for a second, and an entire group spawns in about 3 feet away(and I don't mean from one of the actual spawn points behind the rubble). Thank god for the HW 3D Audio, making the speakers behind me let me know there's a bunch of zombies about to tear me apart.
But yeah, that doesn't happen when the trader is telling me that she's outta here boys. I just get ambushed with no warning.