1unbeliever......that is quite an interesting question that you have asked and i would like to answer it on the basis of 6 years of answering health questions on AB
The are all sort of folk posting in B&S and I am glad to say that most of the case histories are believable and genuine, however there are exceptions but these genuine cases are appreciative of ABers advice.
The annoying ones are those that come onto AB in a panic, ask for advice and then never give any feedback....they just are annoying.....
There are people on here with personality disorders and other types of mental illness which is apparent even to the untrained eye......these are no problem.
Then there are the "attention seekers" those that you are describing who come on with imaginary, obscure and unrelated symptoms to any pattern of disease and AB is a paradise for these people who's attention thirst is quenched by the sympathetic but totally unhelpful replies by the innocent gullible.
Now to Münchhausen by proxy......there is only one poster who, in my opinion displays all the symptoms of this syndrome..............and he/she is thriving on AB
These are my opinions, I am not a Psychiatrist but the symptoms and signs are so clear that one does not need to have a post graduate degree to have a high level of suspicion
Once again an interesting OP, but on balance contributing to B&S is worth while, despite the occasional "sticks and arrows" from certain but predictable directions.