Well I haven't been to Detroit or Michigan but I have always disagreed with people claiming seediness in Scandinavian cities ( and most other cities in Europe ).
All sorts of people live in cities, not only well-to-do people. So you'll see homeless people, beggars etc. in all bigger cities - and so what...
In the center of Scandinavian cities, I wouldn't say that there are purely seedy areas - areas are very mixed.
If you take the area behind the central station in Copenhagen - yes it is considered the 'red light district' but it is also very gentrified in parts. So you'll see all sorts of people there.
And it is not dangerous to walk anywhere in the city centers in Scandinavian cities, period.....

To compare on-the-beaten path of the most touristed cities in each country during the day on a weekend:

When it comes to people around Oslo C, it seems to me that there was obviously a higher proportion of people under the influence of narcotics than I've seen when it comes to people around Grand Central or Penn Station in NYC unless we go back some decades.

When it comes to central Stockholm, Sergeltorg is more notorious than Colombus Circle when it comes to drug dealers and obvious users of restricted narcotics. That is even when there is an open police presence.

When it comes to Copenhagen, prostitution and drug use is to be found rather easily and close to the on-the-beaten tourist track.

Do the Scandinavian capitals have the potential gun violence levels of some of the neighborhoods in the outer boroughs of NYC? No, but in NYC those are now mostly just in areas that are not so close to the high volume tourist traffic paths.

Are the "worst" areas in and around the Scandinavian cities anywhere nearly as dangerous as dangerous neighborhoods in Detroit? No.

I've been to the "most dangerous" neighborhoods in Scandinavia, and in them I felt that the likelihood of an adverse criminal incident impacting me there as a visitor was much lower than it was in some of the wealthier neighborhoods of Washington DC or NYC. I find it rather interesting when my Scandinavian friends and family "warn" me about "dangerous" neighborhoods in their area, as the risk level is entirely different and much lower than what is typical in large US cities and suburbs.

The concept of 'dangerous areas' in Copenhagen is alien to me.
There is nowhere I would be worried to walk during the day or evening time
(I don't roam the city in the middle of the night).
And I don't mind diversity population-wise, so the presence of drug addicts, prostitutes, homeless etc. doesn't bother me.
And as I mentioned in my earlier post, no area is 100 % full of these people.
The Istedgade area behind the central station in Copenhagen has a fairly large population of smart, young people and young families.

So you are basing your dislike for Copenhagen on a busride from Istedgade to Carlsberg the now closed Brewery site being developed over the next 10 years with new apartment’s etc. That is possibly one of the most uninteresting parts of Copenhagen. Istedgade is home to street prostitution (perfectly legal in Denmark) homeless, porn shops, gay saunas and drug addicts and if that was what you saw then yes Copenhagen is not worth anything. But the area is also home to some of the best places to eat and drink and except for the bit aggressive selling tactics of the prostitutes it is actually not that unsafe an area.

Yes Tivoli is Expensive and to be honest Denmark in general is expensive, no doubt about it but there are plenty of things to do, just walk down “Strøget” go to “Nyhavn” and I would also recommend a walk around channels around “Christiansborg”. But to be honest sometimes you need a little more time in a city to find the areas that you like. I frequently traveled to Stockholm a couple of years ago and the first time I was there I was disappointed. I walked down Drottninggatan at night wanting to get something to eat at night and found that here was almost no places to eat there. The next time I discovered that you needed to another area and that changed my perception of the city.

Well I think there are more than one side to that. Danish is a Quite hard language to master and so when people try to speak Danish they often fail bigtime and it can actually be quite hard to understand what people are saying. Also being a so small country everyone is taught English from they are very young, today all kids learn English from first grade so when become adults most understand English perfectly. Therefore it’s so much easier to just speak English. An entirely third reason is the fact that many in the service sector and shops in the Copenhagen area are actually not Danish. Either they are foreigners staying in Denmark or like many, Swedish people working in Copenhagen as the salary in Denmark is quite a lot higher than they would get in Sweden for the same job.

I feel that some people's idea of "seedy" may be that they see activities they morally disapprove of (drug use, prostitution, signs of non-heterosexual behaviour, etc). Those problems are more in their own head than on the street. They may also see people who are not like them (in particular not as rich, well-dressed and socially conforming as them) and wish to dissociate from them, again that is a problem more in their own head.

Not to say that poverty, drug misuse, exploitive sex work, etc are not problems - but I'm discussing the mental attitude of an onlooker, not the effects of the problem.

Some people expect to go only manicured places with clean buildings, the visible people acting being richer ones acting just like them, no signs of behaviour that they find uncomfortable, no poor people or similar - well, there is a place for them and it is Dubai, not Copenhagen.

As noted above, Denmark is very safe, and also you see all there is, instead of the uncomfortable parts being hidden away. Overall, it is a far more equal and pleasant place, if people to see it all, than most of the glitzier parts of the world where if you step away from the facade, the rest is far worse for the local people than any part of Denmark.

Yes, much of it is in the eye of the beholder. And of course cities by their dense nature offer a display different from the countryside.

Unlawful drug trade, unlawful weapons trade, and possibly unlawful sexual exploitation/human trafficking is most commonly viewed as "seedy" in the world. It may even be characterized as such by most of those who believe that criminal prosecution of recreational drug possession/use, weapons and prostitution isn't a great use of state resources. NIMBY comes to mind for such open activity, probably even for many who tolerate or may even engage in such activity themselves and don't fancy criminalization of any or all of those activities.

Of course! How else would there be any Wallander, Fortitude and Dicte?

You left out "The Bridge". :D

You're right. I wrapped up season one at the end of last year and have forgotten to check Netflix, but I see now that season two has been added, so thank you!

Anyone have any experience with the Generator Hostel Copenhagen (or have any other hostel recommendations)? I'm passing through for a night and am looking for a place to stay.

Never stayed at a hostel in Copenhagen - the only two budget options I know and can recommend are the Wakeup hotels and the campsite at Charlottenlund (although the latter was quite some time ago, and did require, well, a tent...)

No experience, sorry.
But I can see that the location is very good and central with easy access from/to the airport with the Metro.
(And the area is not seedy.........).

airbnb option
 

Interesting to read this lengthy debate about how Copenhagen compares to Stockholm, Malmo & Detroit (?) on the criminal front! Interesting diversion, stut!

Returning to the question, we had a good airbnb stay in 2012 near Tivoli and got a room with one queen bed and a single for our son. I checked and I am delighted to see the listing is still valid and the cost is $67 CAD - incl. breakfast!

https://www.airbnb.ca/rooms/68577

If you are looking for value in central CPH, this is your best option.

(IMO the Crowne Plaza is a dump popular with tour groups in a high traffic area. Just saying...........)