This rather optimistic item is to be seen in shops at Dusseldorf Airport.
Now, don't get me wrong. I have nothing against Dusseldorf. Its pleasant enough. It has a river and some nice beer.
But amongst German cities it lacks either anything distinctive (like maybe a "Munich" or a "Berlin" - or even a "Hamburg"), yet also fails to have the kitsch or ironic value of somewhere actually crap - or even dull.
Dusseldorf is not quite even in the middle. Its not exciting, its not distinctive, but it's also not really bland or dull - just good enough not to be actually boring, not quite good enough to be "good".
So, a Dusseldorf t-shirt is no things to all people. You cannot use it to celebrate its crapness - as it isnt - but this garment will not convince anyone you are trumpeting your admiration a truly great city either. And you cannot even wear it ironically in a celebration of mediocrity.
Because its better than that.