Isn't there a way to test an O2 sensor to see if it is any good or not?

For some reason, I remember that you should be able to test the resistance across the leads but I want to be sure. I have them out right now while I am changing out my clutch and would like to test them to make sure they are fine before replacing them. The reason that I am concerned is because the car has been running really rich since the previous owner put off-road pipes on without the MIL eliminators, thus forcing it into limp mode. When I connected my diagnostics software to the ECU, it reported the right bank running too rich, and the O2 sensor lead is very black. The left bank sensors are light-grey like they should be.

Thanks!

 

OK...found some info on the Internet, and posting here in case it would be useful to anyone else:

http://www.mr2.com/TEXT/O2_Sensor.html
http://www.forparts.com/o-21.htm