Connoisseur said:

Today it is known that absinthe does not cause hallucinations. Thujone, once widely believed to be an active chemical in absinthe, is a GABA antagonist; and while it can produce muscle spasms in large doses, there is no direct evidence to suggest it causes hallucinations. It has been speculated that reports of hallucinogenic effects of absinthe were most likely due to poisonous being added to cheaper versions of the drink in the 19th century.

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There's this great topic about it in one of pharmaco series from dale pendell.  Can't really remember which one but it stated that due to the the popularity of the drink a lot of adulterants where added to the cheaper brands. I should look it up again to point out which adulterants.
But anyway a good absinthe should have wormwood in the fermentation vessel and not only added after distilling. You can also add wormwood to vodka or gin or whatever and after maceration distill it again and then ad herbs for additional flavoring and coloring but it just ain't the same.