The light colour generally means a lot. All new/newer taxis have the green light and they are equipped with interior cameras and emergency buttons on the interior B-pillar. Unfortunately, some of the older, unmonitored taxis are now getting the green lights also.
Being/not being stamped into Thailand can only happen at (4). Then you'd have to return to the country you came from. An organised visa run would obviate the potential problem.
I don't think that's the case...
"For those that arrive alone and would like a playmate, we host a wide selection ofin-house Mistresses and slaves ready for your seduction".
There were never "4 Patpong sois", only the privately owned PP1 and PP2, any other sois were Silom sois.
Bobby Arms was in the car park, it wasn't underground, though..