You can definitely find things sold as lager that are not beer -- they are crime against humanity.
We went to a camp site in Falsterbo near Malmø, Sweden one summer. On the way to the beach (which was lovely, by the way) we bought a few tins that were labelled as "Danish" lager at a fairly high price but what the hell, we were on holiday.
First swig my other half took got spat out.
On closer inspection it turned out the "Danish style" lager was actually 3% ABV Swedish glop. SWMBO was very miffed at this slur on her homeland and refused to touch it after that and insisted on drinking the ones we'd brought from her side of the Øresundsbron.
Being the British drainhole I am I had to finish of the Swedish stuff. Waste not, want not!