There are some bands I have seen multiple times in concert and never once were they the intended artist. Case in point is the STEREO MC'S. I saw them three different times in a two year span opening for other acts. They opened for both U2 and Midnight Oil in the same two year span and each time they shocked me with how good they were live.
STEREO MC'S released two records in the early 90's that incorporated a british feel to hip hop. They bought into the whole look and sound of American Hip-hop in a way that was very different from the British artists of today, who have adopted their own take on the style (THE STREETS, DIZZEE RASCAL). Their sound was sample heavy and had a R and B vibe to their beats. They had a couple of minor radio hits with "Elevate My Mind" and "Connected" but then faded into obscurity. I had always wondered how they would translate live, particularly in venues where the audience wasn't into rap. But all three times they won the crowd over with enthusiasm and surpising musical ability.
Seeing that they needed to expand their sound if they wanted more notice they released "Deep, Down and Dirty" which was a more straitforward record musically. They replaced the samples with live instrumentation and even sung on a couple of tracks.
I guess you never know what you'll get by showing up to a concert early.
(mp3) Stereo MC's -- Connected