Speaking as a Lutonian born and bred I can affirm that Luton is an absolute dump. There are many varied reasons for this, many going back to the 60's and 70's
First of all, Luton was "blessed" with the first undercover mall in the UK. It was just plonked right in the heart of the town, ensuring the destruction of many of the more interesting {and aesthetically pleasing} buildings. In short the Luton Arndale ripped the heart out of the town centre... There is an urban myth in Luton that any architect commissioned to build a new shopping centre is taken around the Luton Arndale and then told "that's what we don't want.
Then there is the collapse of manufacturing... Luton, and Dunstable with it, were home to Vauxhall/Bedford, Commer cars, SKF, electrolux, Leyland and many others... all now gone. There was nothing really done to attract new business to Luton, certainly not on the scale as in other southern manufacturing towns such as Reading
Then there is the inner ring road which took over 35 years to complete... completion being long after other towns had realised the error of such roads being bulldozed through... and bit by bit that road destroyed even more of the character of the Town Centre... in effect it acts more like a prison wall to contain the town centre so it can never escape and infect the rest of the town...
then comes the thorny issue of race relations. Whilst it is no longer politically correct to mention racial tensions, there is plenty in Luton... especially involving Muslims... Luton has a long history of militancy amongst it's Muslim population. I remember a Bingo hall in the Asian area of Luton being firebombed for being an affront to Islam {ok so it was a bit insensitive to call it Mecca Bingo but still...} then there was the kebab house that was forced to close because it called itself Kosher Kebabs... I well remember the debate raging about the Muslim population wanting ALL school dinners to be Halal... don't forget Luton is where the EDL started, and is where Tommy Robinson hails from... Whilst I don't condone his views or actions, I know full well how and why he became what he is...
who in hell would want to live in a town with tensions like that?
Then there is the council policy of "if it's green build on it" yes Luton has some lovely large parks... but in general on estates every last green patch has been or is planned to be built on.
In short Luton is a depressing place to live or work.... even now, 25 years after leaving the town, a depression descends over me if I even just pass it on the motorway
I wouldn't say Luton's a dump.... but the best way of going sightseeing is with your eyes tightly shut and a bag over your head!