Most of the time even if u think it was laced it probly wasnt, but it is possible it could be, and if it is ull definitely know it. Only happened to me once out of the hundreds of times I bought weed.
I bought a $10 bag a few years ago, and smoked and ate the whole thing at once without even knowing it had PCP in it. I didnt know much about PCP back then, but the weed was drenched in it...anyways lets just say that was probly the worst and craziest 8 hours of my life. Yea u heard right, like 8 damn hours. It was way too intense to be enjoyable, I could have very easily overdosed or stopped breathing and died from this shit. There were definite hallucinations. I saw this little black demon at all times that was always right out of my vision, I could only see it in peripheals the corner of my eye. PCP will make u stop caring about stuff even if u are dying, I accepted death at one point. Long story short, it was horrible, and I was actually amazed that I woke up the next day and Im alive today...there was hallucinations though but nothing very clear.
Remember when he smoked the PCP on training day? My experience was similar to when it showed it in his view, but even more intense. That was just sight and sound, my body feeling and things going on were very weird.