O2 Sensor on a Carb Engine Question

So, I just had a discussion with an engine calibration engineer on the topic of an O2 lean reading due to a misfire or ignition issue. He confirmed yes, during engine development it has been seen. There is unburnt O2 that the sensor picks up. It also tends to add fuel to compensate for this (PCM controlled fuel injection). Also, in a V style engine, cylinder pressures and other funky things have been observed. This depended on the V angles, number of cylinders and firing orders.