why is everyone fussed about exposed feet? Aside from the safety issue (which is hardly our concern, it is the concern of the passenger)... feet are no more dirty than shoes, perhaps even cleaner because if you aren't wearing shoes you might be more careful where you're actually stepping.
I'd rather have someone with no shoes than someone taking off their shoes and smelling out the lounge with sweaty socks. Same applies on the plane - I'd rather thongs/flip-flops than sweaty socks.
And what's the difference between a pair of thongs/flip-flops and a pair of flat open sandals? Just because the latter is more expensive, or 'designer'?
I don't really see how what people wear impacts on our own travel experience... unless you let it. If we sit in a lounge and boil over for no good reason, that's our own issue, not the offending passenger's. If you want to wear PJs in the lounge, what's wrong with that? Why should it bother anyone else?