It's a pretty run down area and the houses just don't sell. Burnley had a larger population in the 1950's than it did in the early 2000's and it's all down to work. Burnley's population growth was down to people getting employment in the cotton industry and now that is no more. People have moved away because of work (and that's why you won't be more than one mile away from a Burnley fan ).
The town has actually started to grow in the last few years, business and employment wise.
I had a property for sale in Nelson 18 months ago. Had two neighbours approach me before it even went on the market with an offer. Sold it for £28,000, typical 2 up 2 down with kitchen off living room. Hope to get back up for a visit soon. Always got a soft for Burnley. First went to Turf Moor in the early 80's for a reserve game against Everton, it was freezing and Bovril was most welcome.