The ziplock bag idea sounds like a good idea but only after long term storage.
But how do you know if condestation has affected the reliability of the gun causing it to jam, etc? What I do, is simply take
The mag out (and of course any round that might be in the chamber)
And then simply pull the slide back until it stays in the open position, close the slide, powerstroke/open the slide again, close slide, open slide again to full open position, and repeat like 5 times. I assume if the slide is able to open and close then condestation hasn't frozen anything and the gun should be good to go. Am I right?
If you bring a very cold gun inside and do that it will fill with condensation as you're doing that.
Bring it inside in the case, a zip-lok bag, or even a plastic grocery bag and there will be no condensation
as long as you leave the gun in the bag until it warms up to room temperature. Actually, it only has to warm up above the dew point to avoid condensation when you uncase it.