I thought it was a myth, but apparently cactus spines actually do puncture tires.
At least some cactus from my recent Baja trip
did a number on my two passenger-side tires (General Grabber AT2, aired down). I never had this problem in the past with my old BFG T/A KOs, but maybe I was lucky.
After I got back home, I noticed a slow leak in each tire -- a few PSI/day. The soapy water trick turned up bubbles, so I plugged each tire. Slow leak remained. More soapy water turned up more tiny leaks. I found a total of five holes in the right-rear tire and four in the right-front, some in the tread and some in the sidewall. I plugged them all, but there are more to find: I am still getting slow leaks.
So, my question is: should I slime the tires?
They still have plenty of tread on them, so I'd hate to just replace them.