As someone who works and has lived there +6 years I agree. It’s gone downhill sharply in recent times.
The Gardens area has always been horrible but now even Market Street has gone from overcrowded and annoying to cesspool of pure fucking scummishness. Shops that have shut down have been replaced by Poundlands or congregations of alcoholics and the shoppers seem to worse than ever.
I think the trend is that the centre becomes too crowded/ expensive/ whatever and the areas on the fringes start to become decent and get investment (NQ, Anocoats, Spinningfields, that new Granada development). Maybe all city centres are like this I don’t really go anywhere else tbh.