I try to avoid telling unsolicited stories about my kids, but what else am I supposed to answer when people ask about my weekend? It's not that I'm mistaken about how exciting my kids are, it's that other people are mistaken about how exciting (for them) my weekend could possibly be!
Despite not having children, I like hearing about my coworker's and friend's kids. Complaining about them can get old, but funny stories and things they are proud of are great to hear. I don't think I'm unique in this.
I don't mind -- and am often interested in -- cool/funny things about my friends' kids, but the complaining... ugh. I get that kids are far from being all rainbows and sunshine, and I would never begrudge my friends the occasional (or even more than occasional) venting session, but after some threshold of complaining I just want to say "maybe you shouldn't've had kids if all you can do is complain about them".