Why Are There No Butch Lesbians on Television? By Vanessa Vitiello   The femmest of TV lesbians: Brittany (Heather Morris) and Santana (Naya Rivera) inGlee.Photo by Eddy Chen/Fox Thank goodness for The L Word and Portia de Rossi. Before the mid-aughts, when the former premiered and the latter came out of the closet, the pernicious stereotype of the…