GP isn't talking about "wondering if", but rather being distracted by thoughts like "WTF is going on?", "wooow!", "WOOOWOWOWOW!", "is it supposed to be like this?", "oh look at me I NAILED this task", "I think I have been hungry for the past 3 hours but I don't really care, WOW this is nice", etc. You get used to it in a day or two, and most of the "WOW factor" disappears just as fast - point being, one's very first day or two of taking such drugs aren't good as a benchmark.

BTW. with the beer example, it's been measured that part of intoxication effect comes from expectations. As in, you give people non-alcoholic drinks while telling them they're regular ones, and they'll show the usual signs of alcohol influence - worse coordination, stuttering speech, etc. - and snap out of it once told they've been drinking placebo. Reverse also seems true, i.e. early effects are weaker when people think they're drinking placebo while getting the real deal.

(And, N=1, personally I've observed I can "fix" the effect of a beer or two on movement and speech if I consciously remind myself that there's an expectations component to intoxication effect. Of course this works only up to a certain BAC level :).)