Storing unused ultra/super cap, keep terminals opened or shorted ?

[BravoV]

The shorting will be more for preventing the dielectric absorption inside the supercap from charging it up to 2V again over time, or to a reverse voltage.

Exactly.

I'm guessing when stored shorted doesn't have any bad long term effect right ? Especially to the electrodes, electrolytes and etc.

Here mine, from now on its shorted, and separated from the series connections as its quite dangerous.
This particular one, from a fully charged at rated voltage, then drained to 0 volt, if left opened just an overnight, it will bounce back to > 1 volt. 

[XOIIO]

12V 1F, stick your tongue across this.

That's only one farad? Jeeze.

[station240]

I've got a 2,000V capacitor from an old microwave stored with the terminals shorted.
Those also have a reputation for building up a voltage from energy stored in the dialectric somewhere.

As for the 1F car audio caps, many of them are pure wank.
Somewhere online is a review an Australian did of various ones, what the actual values are, and what sort of ballast is inside to make up for the lack of actual capacitor.
One had a huge lump of refactory brick inside.

[SeanB]

Saw that, where one had a half kilo of sand and pitch inside, and a recycled capacitor as the rest. IIRC it was not even 10 000uF.