A lot of places have dodgy parts whether that be London, Plymouth, Portsmouth, Luton, Manchester, Liverpool, and on and on and on.
Personally, having had experience of some of the above, I would say Canning Town in London... Silvertown, Prince Regent whichever bit is the worst, I neither know or care... it is a dreadful, horrible f***pit.
Curious, why do you need to know?
@PinkWhiteRed... for simple degradation... Plymouth outstrips most other parts of the country. It's simply grim as hell. If it were north of Watford or east of Swindon you would never hear the end of it on the News, but hidden away where it is, people leave it be. I go often and it is unbearably sad that such a historic and beautiful city has such a problem, it is where I was born (Beacon Park, Swilly, North Prospect, whatever they wanna call it) - used to live in the house on the corner of North Prospect Road and Beacon Park Road (it was Swilly when I was there, the name changes are indicative and quite important, shows how the problem is tackled, or rather dodged - you wont see Moss-side, St Pauls or Brixton getting name changes, but a new decade brings a new name for that part of Plymouth) and thankfully we moved when I was very young. Would be dead or in clink if we had stayed and if I'd grown up there, no doubt... truly a hideous f***ing hole. Crying shame. If you would rather live in Plymouth than Bristol, you can only have been to the Barbican and Hoe in Plymouth. Excepting the new development at the top end of town, the town centre is like stepping back into the 70's. Literally as though no time had passed since my childhood.
That said, Canning Town is worse. It makes me shudder to think of it. The area between Canning town DLR and Prince Regent Road is a great advert for napalm.