What was the worst band or singer you’ve ever listened to?

I saw Hole play a show years ago and their opener was this god-awful band called Imperial Teen.

Hands-down the worst band I've ever seen.

Now, if you ask about the most disappointing concert I've ever seen, it was the Smashing Pumpkins' Horde Fest run. No one's showing up to hear you mix bongos into your songs and experiment with your music live.