Hard to imagine that anything untowards is happening to the beer inside the cans. The cans themselves may be picking up some mildew aroma, which might be affecting the taste if you are drinking from the can.
If your takin' your girlfriend out tonight
You better park the car well out of sight
'Cos if they catch you in the back seat trying to pick her locks
They're gonna send you back to mother in a cardboard box !