Commonly used in the UK during mid 70s as a disparaging adjective. However, occasionally could be used to describe rock music in a less negative manner, in which context it can also imply "gentle" or "sensitive"
The opposite was generally hellish beef
"Oh, Zeppelin, Sabbath, Heep .... any hellish beef stuff really"
"Yeah me too, Zep are the men - I even like their helluva tame stuff on Zep 3"
Tender: "Wheyyy.... look at that guy with the hellish beef prime Plant locks over there!"
Barker: "Yeah, he looks beef but he's carrying a helluva tame Cat Stevens album under his arm"