I've found the electro-cleaner to be rather temperature sensitive. A
little bit too hot and I would get a gray smudgy streaky thing going
on. I don't know if cooling off the cleaner alone would do the trick,
I just replaced it with a new batch. The label does say do not
overheat. I don't heat as much but zap it longer.
You didn't mention if you use acid dip. Cheap insurance.
Sometimes distance between work and anode seems to have an impact,
too close together and I've gotten the appearance of too high
voltage, that frosty gray look.
I think Phillip is right about silver contamination and religious