Years ago I played in a southern/country rock band and we had the chance to sit in for another band for a gig in a US army club near Mannheim, Germany. After the first two songs we heard comments like "it's Saturday night" (as if we didn't know), "rock n roll", "Black Sabbath", "AC/DC", "turn the radio on", "hang this band". Turned out that Friday was their country day and Saturday their "Rock 'n' Roll day". We should have hanged the agent who got us this gig instead.
With another band I played at a biker festival. I believe they pretty much ignored us the whole first set throughout - just as if we were not there at all. That was easily the most phlegmatic crowd I ever witnessed.
Cheers Stephan