Just remember, you're checking them out too. If it's going to be a chore for you, and not fun at all, there's no point really. I'm assuming you're not a pro needing the money of course? That'd be different, then maybe you'd bite your tongue to get the gig and give them what they want.
However, if this is meant to be an enjoyable experience for you, and you have little or no input into your own sound, then I'd have a problem with that.
If it was me.....I'd see how tonights jam goes, and if at the end you're still not getting the vibe, I'd say thanks fellas, but this aint for me, and leave. They aren't taking the bull by the horns so you might have to.