A full strip during Salome does exist - but the soprano was Maria Ewing, not Lesley Garrett. However, Garrett did once flash her bum in a comic opera (Der Rosenkavalier IIRC). I suspect that the Strauss family name, combined with the knowledge that there was a "dance" in Salome may have led to the Garrett striptease myth.
Now if Cecilia Bartoli could be persuaded to go on arevived Colpo Grosso...... >