So, I've always wondered: what are the economics of lounges?

For oneworld at least, anyone with Sapphire status or better can access any oneworld lounge at any airport (though there seem to be some caveats about contract lounges whose corner cases are not totally clear to me -- can you end up in a situation where you have no lounge access because all the lounges are contract lounges and refuse you access, or do the oneworld rules mean at least one lounge must be made available to you, if there are any oneworld lounges at that location?).

My understanding is that at least in oneworld it is the operating carrier that pays the cost of the lounge (including any guests). So doesn't this incentivise an airline that doesn't have many flights to hand out Sapphire status with wild abandon? The corner case is an airline that offers lifetime status, which might end up effectively getting other airlines to pick up the bill, if the passenger is not / no longer resident in the airline's geography. Or does it all average out equitably, with smaller carriers both less likely to earn money from lounges and less likely to have to pay for access to someone else's lounge?

Also, I think I read somewhere that oneworld has two levels of business lounge (I don't mean first and business, I mean within the business category), something like normal and premium, and the latter obviously costs more to the operating carrier. What stops airlines from declaring every lounge they operate as being premium, to maximise income from other carriers? Is there some kind of specification of what constitutes a premium business lounge, and if so what are the determining criteria?

Finally, would I be correct to assume that if I go lounge surfing, i.e. just pop into a bunch of lounges at an airport just to see what they're like and then pick the best one, this is bad for the operating carrier because they get whacked for the entry fee for each? Would I also be correct to assume that if I leave and reenter the same lounge (on the same day) the operating carrier just pays for one entry?