What do high-end all-inclusive resorts in Mexico dilute spirits & wine with (besides water)? [closed]

I've been delighted with vacations in Mexico from year to year at resorts such as Iberostars and Secrets, but I'm puzzled by the taste of spirits & wine at these high-profile all-inclusives. I know the taste profile of beverages like Crown Royale, Johnnie Walker Blue, Grand Marnier, cabernets, and chardonnays as well as how my body digests them.

While trying many variations of these drinks (neat, on-ice, with water), I am completely sure that there is something diluting them, but its not water (or mexican water). It's more clever than that, but I can't identify it. A pure and sweet cognac like grand marnier tastes dirty. Vodka martinis out of a grey goose bottle have an almost electrical zing that shouldn't be there. The Jonnie Walker blue should have a floral oaky finish, but there's a walloping decay of self-destructing bitter. The house wines have a flavor I would describe as zombie-like (neither dead or alive), and 2 hours later I have the worst heart burn. I don't get this normally.

The effects of the alcohols on my body are also different, when compared on a full stomach. Normally, vodka takes its time to show cognitive effects, then exponentially spikes up; at these resorts its more constant, linear. Two fingers of scotch normally hacks away steadily at my introverted nature until the tree falls and I'm inviting people to dance; at these resorts, there's barely a lead-in with a moderate wallop later on.

Is this common in Mexico or other international all-inclusives? What's going into the alcohol?