i went to the Bier Garden in Portsmouth VA. they have over 300 different beers and a quite knowledgeable staff. one of bartenders claimed that Heineken has formaldehyde in it.
she got a bottle of Heineken and a full glass of water. she opened the beer, put her finger over the hole, turned the beer upside down, submerged the top of the bottle neck into the glass of water, and removed her finger from the hole.
you could see something draining out of the bottle into the water. it was a clear stream that distorted the water, a bit like heat from an exhaust pipe will do to the air.
after about two minutes of draining the formaldehyde from the beer, she put her finger back over the hole, turned the beer right side up, and poured the beer into four glasses and gave me one of them. the Heineken tasted TOTALLY different. it no longer tasted like skunk and arm pit. it now tasted more like rolling rock.
give it a try at home.