Fosse luxuriated in the elements of vulgarity and sleaze in showbiz. His genius was to transform this ““dirty dancing’’ into an idealized energy that found grace in the grotesque and passion in the perverse. Fosse’s ironic eroticism shakes and shimmies in ““Steam Heat’’ from ““Pajama Game’’ (1954) and in ““Big Spender’’ from ““Sweet Charity.’’ To the wonderfully raffish song by Cy Coleman and Dorothy Fields, a line of taxi dancers leans on a rail in atitudes of hilariously seductive exhaustion, soliciting their invisibly lecherous patrons. The climax is an all-out bacchanal to Benny Goodman’s ““Sing, Sing, Sing,’’ in which Elizabeth Parkinson leaps to glory as Ann Reinking first did in ““Dancin’ ’’ (1978). Reinking is one of the key figures who brought ““Fosse’’ together, galvanizing the spirit of an American original.