They will not tell you if the neighbours are horrible - they want to sell the property! You need to spend time in the area and go back at night if you can. Look out for unkempt gardens, tatty property and rubbish. If most property looks well cared for, you will be ok. Go into a local shop or two and ask general questions when you pay. Have a cup of coffee locally and see who comes in. Is there a supermarket handy? Can you get your children into the local schools? Where does the vendor send their children?
When you look at the property, do you feel it could be your home? Could you afford to make big changes or do you want somewhere ready to live in? What do the front doors look like in the street? Have lots of properties had makeovers? I think you get a feel for an area but some people find acceptable things that would put others off. It really depends on what is an absolute "no, no" for you.
When looking at flats I ruled out a few places simply through turning up a bit early and waiting for the estate agent to show up.
For example, at one place there was a Waynetta Slob-type sitting in her stationary (beaten-up) car with all the windows open and loud music blaring out. When I emerged after the viewing she was still there, but now yelling at her small child. Not a good sign.
Another time I heard an argument inside a very nice-looking Victorian property in a pleasant street where I was waiting to see the ground floor flat. Seconds later a bloke burst through the front door (from the upstairs flat) yelling into a phone: "I will f****g kill her". From his erratic behaviour, I guessed he was a druggie.
In both cases I lost interest before setting foot inside.
Another clue is to listen for loud music in neighbouring properties. I heard thumping music during one viewing so went back the next day and knocked on a neighbour's door. They told me chapter and verse about the noisy neighbour one floor up, the harmless person with a learning difficulty on the top floor, who had previously caused flooding by letting her bath overrun, and the high level of vehicle crime and the fact they had been mugged!
So don't be afraid to talk to neighbours as they can let you know about other problem neighbours.