Politicians in safe seats are theoretically accountable but due to the partisan nature of the electorate can in reality do whatever they like. Regardless of how badly they perform, they or their allies will always get re-elected.
In the UK there are some seats like that and they're usually associated with the most hilariously incompetent politicians. Diane Abbott became famous in the last couple of years for all sorts of useless and bad behaviour, like this famous exchange in which she went on the radio to explain a new policy of hiring more police, but repeatedly gave nonsensical and inconsistent numbers for how many and how much it'd cost:
http://www.lbc.co.uk/radio/presenters/nick-ferrari/diane-abb...
e.g. she claimed hiring 10,000 police would cost only 300,000 pounds and when it was pointed out that'd mean paying them 30 pounds a year, she just invented another number on the spot that was also an order of magnitude away from anything that could possibly be correct.
She also routinely posts racist and sexist stuff on Twitter, skips important votes and generally fails at basic politics but her share of the vote went up in the election - because she's Labour.
No competition? No accountability!