I've seen Iron Maiden only once in concert. That was the tour supporting their Somewhere in Time album. Now I don't know exactly how opening acts are selected for major bands, but sometimes I think crappy bands are picked just to make sure the main act isn't upstaged. I had heard ZZ Top did this often. And I became convinced Iron Maiden did it at least once for the show I had seen.
This was the opening band.
Don't get me wrong. I like KISS, and I guess Vinnie Vincent was decent when he was with Gene Simmons and crew, but he absolutely sucked as an opening act for Maiden.
Made me all the more appreciative when Steve Harris and his band took the stage.