I've just caught up with the thread since I logged off to watch TV do something constructive last night.
In my own experience, saying, "actually, that's horrible/offensive/cruel" is never the easy route in social situations, or even on the internet. There is not shortage of people who will be utterly convinced that you are an example of "PCness gorn mad". There are lots of times I look back on with regret, because I didn't object, and just laughed along, with everyone else. I cannot remember ever pretending I thought something was offensive, in order to be like everyone else!
Since we're doing analogies (AF, I'd never heard the simile about the shovel before, and I thought it must mean your car was slow. 
Then I re-read it, and decided in that context, a slow car wouldn't make sense. So then I decided that maybe it depended on whether you were shovelling wet faeces, or flicking dry dung off a shovel. I think they might speed through the air quite nicely), here's one for the the thread topic.
Some people think slipping on bananas is funny to watch. Now, suppose a person (we could call him or her Colin or Nicole) started randomly picking strangers out of the phone book, and planting banana skins in order to cause them to have accidents. Colin/Nicole films all the accidents people have, and posts them on youtube, together with derogatory comments. Other people join in the ridicule there.
Now what's the most important issue here? In my mind, the most important issue isn't that some people find themselves laughing at those videos. The important issue is whether you think Colin/Nicole were reasonable to behave that cruelly in the first place.
If anyone here thinks it's acceptable to ridicule an ordinary person for their appearance, and to copy and paste their personal information all over the internet, together with mocking, belittling commentary, why?