A number of artist have covered this song, including the heavy metal band Great White, who were nominated for a Grammy for it; Hunter was not entirely pleased. It was Great White's biggest hit, peaking at #5 in the US.
"Once Bitten Twice Shy" is an expression meaning that if you've been hurt, you are less likely to put yourself in that position again. In this song, Hunter sings to a girl who seems to take up with lots of musicians. He knows from past experience that he can't count on her.