Of course curb your enthusiasm has bad acting. Larry David's not an actor. Although by now, he should be considered one.
But any bad acting is overshadowed by the plotlines and hilarity of the episode.
To me, entourage doesn't have anything redeeming like that. Nothing special going for it outside of Jeremy Piven. I recognize it has some good supporting actors/actresses in minor roles like Carla Gugino, but of the main 5 characters, only Ari is worth watching.
Fluid, I understand that they are playing characters. That's what acting is. So I'll give them credit there - they've been able to keep an acting job. But the dialogue between the 4 is badly acted, and the weakness of the other 4 especially shows anytime they share screen time with piven.
I just don't get the love for it. And I haven't just watched one episode and stopped. I watched it, didn't like it. But others told me to give it some more shots. I'm open-minded, so I did, and it's still bad.