I rarely do drugs of any kind at home and the only drug i'd ever touch is weed. I'm not stupid enough to even contemplate touching a joint in thailand or laos, but from what I've heard from people who have been to cambodia, it's a pretty much lawless place (despite that, i'm assuming cannabis is technically illegal). Anyway hypothetically if one was to have a joint in Cambodia, and then go back into thailand at the poipet border, what are the chances of being drug tested and caught? And what would the repercussions be for having cannabis in your system?
This is not going to happen. There are stories of Bangkok police busting clubs and drug testing people inside but it's unclear whether this still goes on. I wouldn't worry about it, just be smart and don't buy in the street. And when coming back into Thailand try not to look as if you've just stayed up all night.
Are you kidding? Restaurants throughout the country openly sell it in the form of Happy Shakes and Happy Pizza! I was at a bar in Sihanoukville and joints were on the menu! The authorities aren't going to start harassing precious tourists by giving drug tests at the border! Just don't do anything stupid like try to bring it across.