DC measured through series electrolytic capacitor

This must be a noob question but I will ask anyway:

I have an electrolytical capacitor coupled in series. The + side of the capacitor is connected to 6 Volts of a headphone amplifier circuit output.
With a multimeter I measure the other - side of the capacitor: I measure 6 Volts.

I expected to measure a few mV at most, theoretically 0 Volts. Is this normal behavior due to some voltage leakage and the high impedance of the multimeter?

Almost every capicitor I tried shows this. They cannot all be bad can they?