When I was a teenager, I made one or two trips across the border to Tijuana. In every souvineer shop, they sold Cusano Rojo mezcal... with the worm. I think I might have brought a bottle home, but just looking at it gave me a hangover so I'm not sure I ever drank any.
You can still buy Cusano Rojo, but not at Howie's Market, because we're a little more
sophisticated than that...
We just sell the good stuff, and with the boom in high end tequilas and mezcals over the past 20 years, there's a lot of good stuff out there.
My favorite these days is Yuu Baal Pechuga. Pechuga mezcal initially goes through the typical process of roasting the hearts of the agave plants in an earthen pit, and then distilling the alcohol. To transform the mezcal to mezcal de pechuga, the spirit is redistilled with native Mexican fruits, grain, and nuts, and a raw turkey or chicken breast (!) is hung over the still, cooking over the vapors and adding further complexity to the spirit. This gives the mezcal a bit of an "oily mouthfeel" which sounds gross, but is actually great.
Yuu Baal uses a turkey breast in their distillation, as shown by the slightly psychedli-sized looking turkey on the bottle.