Or "could be dodgy" and "will be dodgy".

Fellow Australian think we are going to have to explain to most of the rest of the world what dodgy means first :)

Anyway shouldn't it be "might be dodgy" and "is dodgy"?

Except the British, or at least Mancunians. "Ugh tastes a bit dodgy" does not sound foreign to me in any way.

How would using more confusing terms help?

"Guaranteed until xxx" - all brands guarantee their products before the best before.

"Hazardous after xxx" - literally, this could kill you after this date.

The other problem is forcing brands to put "hazardous" on their labels.