People who follow this lifestyle tend to think about money more than those who don't.
Notice I didn't say "worry." I said think, which implies cool rationality; we consider and plan our own purchases carefully, and we see the big picture, which gives us a particular kind of insight into others' lives. I frequently wish that I didn't have that insight because it clutters many of my relationships.
Example: two of my neighbors have high school kids and both bought them brand new cars. One told me proudly he has a Disney timeshare. Both pay for trash pickup, landscaping, and have dual SUVs meaning that each family has four cars now. They are absolutely, comically, stereotypically falling over themselves in an attempt to one up each other, no doubt about it.
Taken individually, none of these financial decisions means anything. Taken as a group, your Mustachian sense is now screaming at you that they're struggling to get by because of all of the conspicuous consumption. I can almost see their bills piling up, the car payments and phone plans and hotel bookings, hear the arguments about what they can and can't afford to do every month, and on and on. God help me, I see them in the front yard and I think: You look rich, but you're actually poor and will never retire. IMO, these thoughts are more observation-y than judge-y. (I think.)
Still, I did not see people this way 15 years ago, and I think I'm the worse for it.
I'm taking the long way around to saying that I wish my brain didn't put people into financial buckets and figure out where their money is going -- it's not constructive and it's certainly none of my business -- but it seems to happen auto-magically nowadays. It's not like I obsess over it -- it doesn't take very long to put the clues together - just a few observations, and viola! We have our result.
Sorry, I realize this thread said "just for fun" and I've made my response very un-fun. Hopefully I can get away with that, because hey, I'm Dr. Doom.