Yes, I'm interested in the culture of disbelief on here, too, and in what precisely seems to be singled out for disbelief (which often seems to centre on income and having a spouse or partner who isn't a porn-guzzling Neanderthal who cooks, cleans and looks after the children?)
I mean, I suppose I come on here because it gives little insights into how people actually think under their social surfaces, their approaches to things like friendships, happiness, the world of work, relationships, relations with family, social class, money etc, and also, maybe more interestingly, their assumptions about what is 'normal' in relation to these, which I think are much less censored than in RL.
There are things that I genuinely only encounter on Mn as well (I don't know anyone in RL who is so obsessively concerned with the cleanliness of their house, who has even a concept of 'visitor-ready', who thinks that being a SAHP is a 'fortunate' or 'lucky' thing -- to mention only a couple that immediately come to mind), but I have no doubt that these people are as real as I am.
I do have an intelligent, grounded friend who says she found that MN was bad for her MH, that the numerous threads criticising people's parenting, or about children misbehaving in public etc made her feel appallingly self-conscious about being in the supermarket with her autistic sons, so she stopped using Mn because it made her feel worse about herself.