Every major European city has a seedy underbelly and I guess this is Copenhagen's. Only it's not…read moremuch of an underbelly as it's so visible, so maybe an.. elbow? In any case, this is where you can see many of the local prostitutes and drug addicts. They are normally not aggressive as long as you avoid eye contact, so just be cool. Wait, where are you going? Come back, it is really worth a visit.
For one thing, there are a lot of great restaurants here or on its side streets; especially if you want Asian food. Although Magasasa and Thai Corner scream "tourist trap!" due to their close proximity to the central station, you can get good, authentic food. After that you'll want a drink, and it's easy to roll your distended belly down to Ølbutikken or Mikkeller. And if you drink one too many, drag yourself further down to Kebabistan for that late night stomach-padding.
Although it is sort of an ugly street, it has its own charm and so many nice places to eat and drink. Just refrain from buying any people or drugs and you'll have a great time.
Food: Bento, Magasasa, Thai Corner, Noodle House, Fu Hao, Kebabistan
Drink: Ølbutikken, Mikkeller, 1656, Dia'legd
Shop: Rude, Hornecker, Ølbutikken