How low is too low for a laugh?

I find it hard to watch modern movies in the company of my parents. Pretty much every movie I have ever seen contains something I would describe as 'objectionable' and cringe-worthy in their presence.
I remember a time when we had what were loosely described as 'censors', people who were paid to watch movies and tell us which ones we ought to avoid. These days its clear anything goes if you at least aim for an M rating. Even comedy shows on TV are riddled with F bombs and other material that embarrass me to hear.
I was not brought up with swearing and the only time an expletive has passed my lips is when I am quoting what someone else has said. My brother Anthony chided me when I was a teenager when I said, "shit" : "Does that strengthen your argument if you add a swear word?" I thought about it for a while searching for a defense.
To my shame I admit he rightly picked up on my weakness. And now when I hear someone shouting out their Fs and their Cs I know their argument must be flawed. We need to offend if our intelligent attack is weak.
Despite spending a lot of time around police and footballers, I still find it shocking to hear swearing. And even more so when it comes out of the mouth of a woman. Its just so unnecessary.
I do not honestly know any Tagalog rude words so as I listen to people in the Philippines I never hear once offensive word. Unlike walking down the street of any Australian town, I am appalled even by the little children who cuss.
But I was absolutely appalled (that's even worse than just being appalled) when I watched a recent rant from comedian Adam Hill. Lucky I was wearing my earphones! He was ripping into Joan Rivers over some disparagement he heard from the aging American comic over the English singer's size.
As you would all know Joan Rivers makes a living out of critiquing other people's body shapes because she spent a fortune modifying her own. But I have a particular bias towards her after watching her win a season of the Celebrity Apprentice USA. She was very raw and emotional in her defense of criticisms leveled at her own daughter during the competition. She was also very generous in delivering services for charities that she had no need to do. In her altruism I saw the softer side of Joan and she often burst into tears when other contestants got aggressive towards her.
Now I don't even want you to go and watch Adam Hill's beserko attack of Joan because it was not even funny (apart from the last line when he tells Joan to "manufacture herself a new soul"). The rest of it was shallow vitriol which can hardly be classified as comedy.
Comedy is generally meant to make you feel good. It makes you laugh with, not at, the target of the humour. I find the current version of comedy that we see dished out by comics shallow on content and deep in dirt.

It is easy to make fun of people for they way they look. For most of us without big bank balances, we can't do much about it. If people wanted to ridicule me for being bald, I can't really go out and buy a new head of hair. So why mock people for their appearance?
Even Hill's comments calling Adele "hot" is also an opinion whose relevance would vary depending on the beholder.
Why do we put so much emphasis on appearance? When I watch the news each night we see a variety of people speaking on various topics from politics to health to religion. But you don't see them being critiqued on what they looked like and their opponents don't malign them with expletives.
I think we need to look at how low we are diving for things to make fun of in entertainment and we need to lift our game if we want our children to look up to us.
As I often reflect, how low is too low in the quest for a laugh?