Yes it is, but I'm OK with a a little discomfort when the alternative is paying 20¢ or more - sometimes a LOT more - per kWh.But isn't that when you'd need it most (assuming cost follows demand)?
My rate occasionally goes negative on summer mornings. I believe this is because they are bringing on capacity in anticipation of demand later in the day. That's when I want to run my A/C, when they're paying me to run it. I'll turn the house into an ice box in the early morning and if it gets too warm for an hour in the late afternoon, so be it.