Transitive, Intransitive and which particle should be used.

[furrykef]

Grammatically 飲みたい is like an adjective though... for the same reason you don't say Ｘをむずかしい you don't say Xを飲みたい。

Really? Would you say ミルクが飲まない instead of ミルクを飲まない? After all, ない is an adjective.

My own experience is limited, but from pretty much everything I've heard, there's nothing wrong with using を with -tai forms. Yes, some people, including native Japanese speakers, will recommend が, but by and large they're used with を nowadays.

Here is part 1 and part 2 of Tae Kim's take on the matter.

- Kef

[Yudan Taiteki]

My vague reference to the たい forms was that you typically don't use たい forms for non-volitional verbs (there are some exceptions, of course).