Interesting. I personally have never waited longer than 15 minutes for The Arrival showers, and in that case they're almost certainly faster than the somewhat frowned upon method you're discussing. I did read another fellow say he once waited for an hour, which is nuts. CX has gotta do something about that. Totally defeats the purpose of arrival showers.

Cathay Boy, I don't think it was explained clearly. Immigration will be properly cleared each time. Someone from CX or security personnel will escort the airside (departure) passenger to a side door and elevator, which brings the passenger downstairs to arrivals. Once downstairs on the arrivals level, that passenger will find himself in the flow of arriving passengers, and still must clear immigration before being allowed into HK. And, in order to return to the airside (departure) section, he/she will need to go back through exit immigration. In my experiences doing this, CX tries to ascertain your reason for leaving and the implication is this is not something to be abused.

Basically, what happens if your plans change after clearing immigration but before you board your flight? This is the method to exit the airport. I've done it once or twice myself (out of hundreds of departing flights from HKG), although I had personal issues arise unrelated to lounge hopping. So I have no doubt it's feasible, legal and available to be (ab)used in the manner susiesan mentions. I just hope it doesn't become prevalent because the proposed reason is not why this safety valve exists. I have also heard of more egregious abuses, guys who buy a J or F ticket, go airside, hang out in the lounge all day for free grub, and then cancel their ticket. The way they exit the airport is in the manner described.