Fans of the "Shake It Off" singer cannot be underrated
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Taylor Swift's earliest tours featured appearances from Katy Perry, Justin Bieber and John Mayer
Generally there's a longer wait list to get Biebz, Katy Perry and John Mayer to make stop-offs on your tour. This was in 2009 into 2010. Swift's stock has, for now, outlasted Bieber's and transcended into diss songs and friendships with his exes. Katy Perry and Swift now fight over backup dancers and top notch talent for their tours. And Swift even dated Mayer at one point. She's always been on the fast track.