To me the whole thing that makes it confusing for me is that real slider switches are labeled externally:

     +-------+
 OFF |   |XXX| ON
     +-------+

That's much more clear. You could even put a little red "lamp" next to the on which lights up when ths swtich is on and darkens when it is off.

Putting the label under the sliding part of the control is what makes it confusing.

EDIT: just noticed that huhtenberg posted the same suggestion