The one I selected from a mind-boggling range was the Don Lucio 100% agave, unaged. I thought the label looked nice, and made it appear that the producer cares about making a quality product, despite the worms and salt sack.
The mezcal within was very nice. Pretty smokey and leathery and probably more rustic than refined, but I really enjoyed it, and at least the agave content meant there weren't industrial alcohols added to it.
And I couldn't not try the worms, obviously!
They're apparently a recent addition, but supposedly add flavour, despite being already cured in alcohol before being added to the mezcal. The larvae used are often Picudo larvae, which are usually roasted and eaten as a seasonal specialty in Southeastern Mexico, so they can't be that bad, and call me odd but I do like the idea of roasted larvae. Most grub species that are used in mezcal live in the agave plants, and some can cause devastating damage to the crop, so putting them in booze and then eating them is some kind of revenge. I was unable to identify the exact species in my mezcal so can't give you more details on that. Anyone know?
The urban myth of hallucinogenic qualities is just that, and I doubt any variety of caterpillar used in mezcal has mind-altering properties other than it being mainly made up of alcohol by the time it's consumed.
Verdict: No flavour whatsoever. Barely enough texture to be exciting or disgusting. Got the willies a bit when I was holding a worm and biting into it, so that provided a bit of fun - I actually imagined the thing moved! It was like biting into an undercooked french bean or chewing on a bit of connective tissue. Quite chewy but not difficult to swallow. Not unpleasant but not enough anything to be pleasant either. In short, this was a pointless exercise gastronomically, but satisfied my own curiosity. I ate both worms as I can't bear to waste 'food', but they would be far nicer fried up with some garlic and salt than pickled in mezcal. I can't imagine they give off much flavour either, but would love to taste a before-and-after.