How does comedy treat the vulnerable?

I'm certainly not excusing the evil behaviour of Wayne Rogers, and his fellow "carers" at Winterbourne View, but I think it's important to examine how attitudes towards vulnerable people may be formed.

Obviously, Wayne and his gang were sadistic people who enjoyed torturing the weak, as revealed on Tuesday's Panorama (viewable until Wednesday 30th May 2012).

However, the depiction of mental illness and learning difficulties in popular culture does shape people's views, and one obvious example is the tedious Little Britain.

One series of sketches has the mental patient Ann, a man who makes shrieking noises over and over again. Ann is only pretending to be mentally ill, as he is able to have a normal conversation at the end of each sketch.

UPDATE: The comment below says that Anne is based on himself and other patients a clinic that David Walliams was in. My unease at how some viewers interpret the character remains though.

The audience are meant to laugh at Ann's shrieking, touching of people and the fact he's not really mentally ill. The sketch reinforces the views of people who think the mentally ill are just "putting it on".

And, as someone with a mental health condition, I despise Matt Lucas and David Walliams for having contributed to the lack of understanding people have for the vulnerable.

What other examples can you think of where comedy, or other forms of popular culture, present a negative image of vulnerable people?