Ok I enjoyed reading those threads and it probably wouldn't be worth the hassle just for lounge access but then...I started thinking...
1. Buy 1 x Y seat at the best price
2. Buy full fare F seat on the same flight
3. Perform OLCI for both seats, ensuring print 2 of the same F boarding passes.
4. Check-in and clear customs with the Y BP.
5. Enter the F lounge with the F BP and enjoy.
6. On leaving lounge, cancel the F seat and pass the gate check using Y BP.
7. Board the aircraft using F BP and go to the (now) unsold F seat.
At what point they print the customer manifest and the FAs would notice a body in that unsold seat.
I know I wouldn't have the nerve to pull it off and enjoy the ride, but others might. I'm sure that they would have a system tocover this...wouldn't they?