The two BIG ‘killers’ of beer is temperature and age. Light can be a problem but as you noted that can be easily ‘managed’ by proper packaging and store handling. Unfortunately the retailers in the US often present the beers in stand-alone six-packs either on shelves (under fluorescent lighting) or in glass door refrigerators which have fluorescent lights within them. Skunking is a genuine concern under these store conditions. Here is a thread I just posted which discusses the Pilsner Urquell Freshness Initiative and the steps they take to combat the three enemies of temperature, time and light: http://beeradvocate.com/community/threads/recommended-euro-lagers.60232/#post-813333 Cheers!