Any decent meter will measure resistance with a voltage lower than about 0.7 volts on most scales, so will not turn on diode or transistor junctions. Thus, you can measure more than you might think with little trouble. Still, there will often be other resistive paths, or large power supply caps that pull the readings down. As c.coyle says, you can't get a false high from paralleled "stuff", with one exception. If there's residual voltage on caps, that can throw things off in either direction, but it's usually obvious. Just measure in both directions. If the answer is wildly different, suspect residual voltages. I sometimes put a jumper right across the filter caps to avoid this, but never forget to remove that jumper! Even with paralleled "stuff", readings should be similar between both channels.