There are few things worse than a tribute band who go half-arsed into the looky-likey side of it, be it through crap, cheap looking wigs and clothes or only one or two of them doing it at all. Step forward Slash from your average Guns 'n' Roses tribute. If you're going to do the Stars in Your Eyes thing, take it very seriously or do not bother at all.
It should go without saying that a tribute act should have the music nailed and nailed hard.